Add migration versions (#3574)

Since Rails 5.1 missing migration version results in following error:

```
StandardError: Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for:
```

This PR fixes all migration files.

23 files changed, 23 insertions, 23 deletions

diff --git a/db/migrate/20160220174730_create_accounts.rb b/db/migrate/20160220174730_create_accounts.rb
index 65c15f3e8..daf7c6552 100644
--- a/db/migrate/20160220174730_create_accounts.rb
+++ b/db/migrate/20160220174730_create_accounts.rb
@@ -1,4 +1,4 @@
-class CreateAccounts < ActiveRecord::Migration
+class CreateAccounts < ActiveRecord::Migration[4.2]
   def change
     create_table :accounts do |t|
       t.string :username, null: false, default: ''
diff --git a/db/migrate/20160220211917_create_statuses.rb b/db/migrate/20160220211917_create_statuses.rb
index 5e62e95be..b17468568 100644
--- a/db/migrate/20160220211917_create_statuses.rb
+++ b/db/migrate/20160220211917_create_statuses.rb
@@ -1,4 +1,4 @@
-class CreateStatuses < ActiveRecord::Migration
+class CreateStatuses < ActiveRecord::Migration[4.2]
   def change
     create_table :statuses do |t|
       t.string :uri, null: false, default: ''
diff --git a/db/migrate/20160221003140_create_users.rb b/db/migrate/20160221003140_create_users.rb
index c9750c623..267466a94 100644
--- a/db/migrate/20160221003140_create_users.rb
+++ b/db/migrate/20160221003140_create_users.rb
@@ -1,4 +1,4 @@
-class CreateUsers < ActiveRecord::Migration
+class CreateUsers < ActiveRecord::Migration[4.2]
   def change
     create_table :users do |t|
       t.string :email, null: false, default: ''
diff --git a/db/migrate/20160221003621_create_follows.rb b/db/migrate/20160221003621_create_follows.rb
index afec3dee0..17287d09b 100644
--- a/db/migrate/20160221003621_create_follows.rb
+++ b/db/migrate/20160221003621_create_follows.rb
@@ -1,4 +1,4 @@
-class CreateFollows < ActiveRecord::Migration
+class CreateFollows < ActiveRecord::Migration[4.2]
   def change
     create_table :follows do |t|
       t.integer :account_id, null: false
diff --git a/db/migrate/20160222122600_create_stream_entries.rb b/db/migrate/20160222122600_create_stream_entries.rb
index 10a6862d9..00782abc3 100644
--- a/db/migrate/20160222122600_create_stream_entries.rb
+++ b/db/migrate/20160222122600_create_stream_entries.rb
@@ -1,4 +1,4 @@
-class CreateStreamEntries < ActiveRecord::Migration
+class CreateStreamEntries < ActiveRecord::Migration[4.2]
   def change
     create_table :stream_entries do |t|
       t.integer :account_id
diff --git a/db/migrate/20160222143943_add_profile_fields_to_accounts.rb b/db/migrate/20160222143943_add_profile_fields_to_accounts.rb
index 221142bdd..cf279a535 100644
--- a/db/migrate/20160222143943_add_profile_fields_to_accounts.rb
+++ b/db/migrate/20160222143943_add_profile_fields_to_accounts.rb
@@ -1,4 +1,4 @@
-class AddProfileFieldsToAccounts < ActiveRecord::Migration
+class AddProfileFieldsToAccounts < ActiveRecord::Migration[4.2]
   def change
     add_column :accounts, :note, :text, null: false, default: ''
     add_column :accounts, :display_name, :string, null: false, default: ''
diff --git a/db/migrate/20160223162837_add_metadata_to_statuses.rb b/db/migrate/20160223162837_add_metadata_to_statuses.rb
index 7120e582a..d11d5f5cd 100644
--- a/db/migrate/20160223162837_add_metadata_to_statuses.rb
+++ b/db/migrate/20160223162837_add_metadata_to_statuses.rb
@@ -1,4 +1,4 @@
-class AddMetadataToStatuses < ActiveRecord::Migration
+class AddMetadataToStatuses < ActiveRecord::Migration[4.2]
   def change
     add_column :statuses, :in_reply_to_id, :integer, null: true
     add_column :statuses, :reblog_of_id, :integer, null: true
diff --git a/db/migrate/20160223164502_make_uris_nullable_in_statuses.rb b/db/migrate/20160223164502_make_uris_nullable_in_statuses.rb
index 0fc1c39c3..24b9b6e19 100644
--- a/db/migrate/20160223164502_make_uris_nullable_in_statuses.rb
+++ b/db/migrate/20160223164502_make_uris_nullable_in_statuses.rb
@@ -1,4 +1,4 @@
-class MakeUrisNullableInStatuses < ActiveRecord::Migration
+class MakeUrisNullableInStatuses < ActiveRecord::Migration[4.2]
   def change
     change_column :statuses, :uri, :string, null: true, default: nil
   end
diff --git a/db/migrate/20160223165723_add_url_to_statuses.rb b/db/migrate/20160223165723_add_url_to_statuses.rb
index a5aa1613a..80f4b3289 100644
--- a/db/migrate/20160223165723_add_url_to_statuses.rb
+++ b/db/migrate/20160223165723_add_url_to_statuses.rb
@@ -1,4 +1,4 @@
-class AddUrlToStatuses < ActiveRecord::Migration
+class AddUrlToStatuses < ActiveRecord::Migration[4.2]
   def change
     add_column :statuses, :url, :string, null: true, default: nil
   end
diff --git a/db/migrate/20160223165855_add_url_to_accounts.rb b/db/migrate/20160223165855_add_url_to_accounts.rb
index 59dd2b97b..c81b1c64f 100644
--- a/db/migrate/20160223165855_add_url_to_accounts.rb
+++ b/db/migrate/20160223165855_add_url_to_accounts.rb
@@ -1,4 +1,4 @@
-class AddUrlToAccounts < ActiveRecord::Migration
+class AddUrlToAccounts < ActiveRecord::Migration[4.2]
   def change
     add_column :accounts, :url, :string, null: true, default: nil
   end
diff --git a/db/migrate/20160223171800_create_favourites.rb b/db/migrate/20160223171800_create_favourites.rb
index bb35f491f..64f5cf119 100644
--- a/db/migrate/20160223171800_create_favourites.rb
+++ b/db/migrate/20160223171800_create_favourites.rb
@@ -1,4 +1,4 @@
-class CreateFavourites < ActiveRecord::Migration
+class CreateFavourites < ActiveRecord::Migration[4.2]
   def change
     create_table :favourites do |t|
       t.integer :account_id, null: false
diff --git a/db/migrate/20160224223247_create_mentions.rb b/db/migrate/20160224223247_create_mentions.rb
index 095f6b7d2..6dd742d3b 100644
--- a/db/migrate/20160224223247_create_mentions.rb
+++ b/db/migrate/20160224223247_create_mentions.rb
@@ -1,4 +1,4 @@
-class CreateMentions < ActiveRecord::Migration
+class CreateMentions < ActiveRecord::Migration[4.2]
   def change
     create_table :mentions do |t|
       t.integer :account_id
diff --git a/db/migrate/20160227230233_add_attachment_avatar_to_accounts.rb b/db/migrate/20160227230233_add_attachment_avatar_to_accounts.rb
index 99d88e5ec..c107c4c7f 100644
--- a/db/migrate/20160227230233_add_attachment_avatar_to_accounts.rb
+++ b/db/migrate/20160227230233_add_attachment_avatar_to_accounts.rb
@@ -1,4 +1,4 @@
-class AddAttachmentAvatarToAccounts < ActiveRecord::Migration
+class AddAttachmentAvatarToAccounts < ActiveRecord::Migration[4.2]
   def self.up
     change_table :accounts do |t|
       t.attachment :avatar
diff --git a/db/migrate/20160305115639_add_devise_to_users.rb b/db/migrate/20160305115639_add_devise_to_users.rb
index 236a4b27c..0e12e6053 100644
--- a/db/migrate/20160305115639_add_devise_to_users.rb
+++ b/db/migrate/20160305115639_add_devise_to_users.rb
@@ -1,4 +1,4 @@
-class AddDeviseToUsers < ActiveRecord::Migration
+class AddDeviseToUsers < ActiveRecord::Migration[4.2]
   def self.up
     change_table(:users) do |t|
       ## Database authenticatable
diff --git a/db/migrate/20160306172223_create_doorkeeper_tables.rb b/db/migrate/20160306172223_create_doorkeeper_tables.rb
index d89b005c3..9e173a43f 100644
--- a/db/migrate/20160306172223_create_doorkeeper_tables.rb
+++ b/db/migrate/20160306172223_create_doorkeeper_tables.rb
@@ -1,4 +1,4 @@
-class CreateDoorkeeperTables < ActiveRecord::Migration
+class CreateDoorkeeperTables < ActiveRecord::Migration[4.2]
   def change
     create_table :oauth_applications do |t|
       t.string  :name,         null: false
diff --git a/db/migrate/20160312193225_add_attachment_header_to_accounts.rb b/db/migrate/20160312193225_add_attachment_header_to_accounts.rb
index bdd09c367..ac9562cbb 100644
--- a/db/migrate/20160312193225_add_attachment_header_to_accounts.rb
+++ b/db/migrate/20160312193225_add_attachment_header_to_accounts.rb
@@ -1,4 +1,4 @@
-class AddAttachmentHeaderToAccounts < ActiveRecord::Migration
+class AddAttachmentHeaderToAccounts < ActiveRecord::Migration[4.2]
   def self.up
     change_table :accounts do |t|
       t.attachment :header
diff --git a/db/migrate/20160314164231_add_owner_to_application.rb b/db/migrate/20160314164231_add_owner_to_application.rb
index 7d5e6d07d..1919f09a1 100644
--- a/db/migrate/20160314164231_add_owner_to_application.rb
+++ b/db/migrate/20160314164231_add_owner_to_application.rb
@@ -1,4 +1,4 @@
-class AddOwnerToApplication < ActiveRecord::Migration
+class AddOwnerToApplication < ActiveRecord::Migration[4.2]
   def change
     add_column :oauth_applications, :owner_id, :integer, null: true
     add_column :oauth_applications, :owner_type, :string, null: true
diff --git a/db/migrate/20160316103650_add_missing_indices.rb b/db/migrate/20160316103650_add_missing_indices.rb
index 190241833..8b6bc5771 100644
--- a/db/migrate/20160316103650_add_missing_indices.rb
+++ b/db/migrate/20160316103650_add_missing_indices.rb
@@ -1,4 +1,4 @@
-class AddMissingIndices < ActiveRecord::Migration
+class AddMissingIndices < ActiveRecord::Migration[4.2]
   def change
     add_index :users, :account_id
     add_index :statuses, :account_id
diff --git a/db/migrate/20160322193748_add_avatar_remote_url_to_accounts.rb b/db/migrate/20160322193748_add_avatar_remote_url_to_accounts.rb
index 9dc4b027f..f9c213d9b 100644
--- a/db/migrate/20160322193748_add_avatar_remote_url_to_accounts.rb
+++ b/db/migrate/20160322193748_add_avatar_remote_url_to_accounts.rb
@@ -1,4 +1,4 @@
-class AddAvatarRemoteUrlToAccounts < ActiveRecord::Migration
+class AddAvatarRemoteUrlToAccounts < ActiveRecord::Migration[4.2]
   def change
     add_column :accounts, :avatar_remote_url, :string, null: true, default: nil
   end
diff --git a/db/migrate/20160325130944_add_admin_to_users.rb b/db/migrate/20160325130944_add_admin_to_users.rb
index e386d33dd..b0cd35e00 100644
--- a/db/migrate/20160325130944_add_admin_to_users.rb
+++ b/db/migrate/20160325130944_add_admin_to_users.rb
@@ -1,4 +1,4 @@
-class AddAdminToUsers < ActiveRecord::Migration
+class AddAdminToUsers < ActiveRecord::Migration[4.2]
   def change
     add_column :users, :admin, :boolean, default: false
   end
diff --git a/db/migrate/20161006213403_rails_settings_migration.rb b/db/migrate/20161006213403_rails_settings_migration.rb
index 3bfd8af8e..3b2e637fc 100644
--- a/db/migrate/20161006213403_rails_settings_migration.rb
+++ b/db/migrate/20161006213403_rails_settings_migration.rb
@@ -1,7 +1,7 @@
 MIGRATION_BASE_CLASS = if ActiveRecord::VERSION::MAJOR >= 5
   ActiveRecord::Migration[5.0]
 else
-  ActiveRecord::Migration
+  ActiveRecord::Migration[4.2]
 end
 
 class RailsSettingsMigration < MIGRATION_BASE_CLASS
diff --git a/db/migrate/20170112154826_migrate_settings.rb b/db/migrate/20170112154826_migrate_settings.rb
index f6f6ed531..0f5afe1d3 100644
--- a/db/migrate/20170112154826_migrate_settings.rb
+++ b/db/migrate/20170112154826_migrate_settings.rb
@@ -1,4 +1,4 @@
-class MigrateSettings < ActiveRecord::Migration
+class MigrateSettings < ActiveRecord::Migration[4.2]
   def up
     remove_index :settings, [:target_type, :target_id, :var]
     rename_column :settings, :target_id, :thing_id
diff --git a/db/migrate/20170330164118_add_attachment_data_to_imports.rb b/db/migrate/20170330164118_add_attachment_data_to_imports.rb
index 4850b0663..2deda1886 100644
--- a/db/migrate/20170330164118_add_attachment_data_to_imports.rb
+++ b/db/migrate/20170330164118_add_attachment_data_to_imports.rb
@@ -1,4 +1,4 @@
-class AddAttachmentDataToImports < ActiveRecord::Migration
+class AddAttachmentDataToImports < ActiveRecord::Migration[4.2]
   def self.up
     change_table :imports do |t|
       t.attachment :data