Update migrations to include their versions

db/migrate/20141130153941_create_problems.rb

@@ -1,4 +1,4 @@
-class CreateProblems < ActiveRecord::Migration
+class CreateProblems < ActiveRecord::Migration[4.2]
   def change
     create_table :problems do |t|
       t.string :title

db/migrate/20141213151812_rename_problems_table_to_translations.rb

@@ -1,4 +1,4 @@
-class RenameProblemsTableToTranslations < ActiveRecord::Migration
+class RenameProblemsTableToTranslations < ActiveRecord::Migration[4.2]
   def change
     rename_table :problems, :translations
   end

db/migrate/20141214214958_create_problems_again.rb

@@ -1,4 +1,4 @@
-class CreateProblemsAgain < ActiveRecord::Migration
+class CreateProblemsAgain < ActiveRecord::Migration[4.2]
   def change
     create_table :problems do |t|
       t.timestamps null: true

db/migrate/20141214220056_add_translation_to_problem.rb

@@ -1,4 +1,4 @@
-class AddTranslationToProblem < ActiveRecord::Migration
+class AddTranslationToProblem < ActiveRecord::Migration[4.2]
   def change
     add_reference :problems, :translation, index: true
   end

db/migrate/20141214221259_add_problem_to_translation.rb

@@ -1,4 +1,4 @@
-class AddProblemToTranslation < ActiveRecord::Migration
+class AddProblemToTranslation < ActiveRecord::Migration[4.2]
   def change
     add_reference :translations, :problem, index: true
   end

db/migrate/20150131103802_devise_create_admins.rb

@@ -1,4 +1,4 @@
-class DeviseCreateAdmins < ActiveRecord::Migration
+class DeviseCreateAdmins < ActiveRecord::Migration[4.2]
   def change
     create_table(:admins) do |t|
       ## Database authenticatable