title: Symfony2 - add flashbag message on entity operations
body: <p>I'm working on a Symfony2.3.6 project, and it works good. I've made a backend side with a few CRUD for some Entities, and it also work good.  </p>
  
  <p>Now what I want to do is notify an user when an operation is made on an entity. So I want to notify when an entity is saved, updated or deleted, as Symfony1.4 made. 
  I was in doubt where to put the flashbag message, if in the entity or in the controller or even with events?!</p>
  
  <p>Which is the right place where I can put this kind of feature, and how I can do it?
  Thanks...</p>