after_find after_initialize回调方法

虽然api没写，但rails支持after_find after_initialize的回调方法

完整的callback是：

 

%w{after_find after_initialize before_save after_save before_create after_create before_update after_update before_validation after_validation before_validation_on_create after_validation_on_create before_validation_on_update
after_validation_on_update before_destroy after_destroy}