Make otp_backup_codes a text field

db/migrate/20150331183602_add_devise_two_factor_backupable_to_users.rb

 class AddDeviseTwoFactorBackupableToUsers < ActiveRecord::Migration
   def change
-    add_column :users, :otp_backup_codes, :string, array: true
+    add_column :users, :otp_backup_codes, :text
   end
 end

db/schema.rb

@@ -492,6 +492,11 @@ ActiveRecord::Schema.define(version: 20150502064022) do
     t.string   "bitbucket_access_token"
     t.string   "bitbucket_access_token_secret"
     t.string   "location"
+    t.string   "encrypted_otp_secret"
+    t.string   "encrypted_otp_secret_iv"
+    t.string   "encrypted_otp_secret_salt"
+    t.boolean  "otp_required_for_login"
+    t.text     "otp_backup_codes"
     t.string   "public_email",                  default: "",    null: false
   end