Store role_id as an integer instead of a string

db/migrate/20130423231937_alter_user_roles.rb

@@ -3,6 +3,7 @@ class AlterUserRoles < ActiveRecord::Migration
     rename_table :user_roles, :user_role_joins
     change_table :user_role_joins do |t|
       t.rename :role, :role_id
+      t.change :role_id, :integer
     end
   end
 end

db/schema.rb

@@ -155,7 +155,7 @@ ActiveRecord::Schema.define(:version => 20130424005701) do
   end
 
   create_table "user_role_joins", :force => true do |t|
-    t.string   "role_id"
+    t.integer  "role_id"
     t.datetime "created_at", :null => false
     t.datetime "updated_at", :null => false
     t.datetime "ends"