Rename deprecated attributes from comments

To avoid deprecation warning thrown by Globalize after gem update.

db/migrate/20190218122530_rename_old_translatable_attibutes_in_comments.rb

@@ -0,0 +1,5 @@
+class RenameOldTranslatableAttibutesInComments < ActiveRecord::Migration[4.2]
+  def change
+    rename_column :comments, :body, :deprecated_body
+  end
+end

db/schema.rb

@@ -428,7 +428,7 @@ ActiveRecord::Schema.define(version: 20190607160900) do
   create_table "comments", force: :cascade do |t|
     t.integer  "commentable_id"
     t.string   "commentable_type"
-    t.text     "body"
+    t.text     "deprecated_body"
     t.string   "subject"
     t.integer  "user_id",                            null: false
     t.datetime "created_at"