Build RESTfull APIs easily with Symfony

Let's build a nice REST API with all the recent helper we can find.
First of all, we will take some time to see, in theory, what's asked to build a Restful API.
Then we'll see some code with the usage of :
- FOSRestBundle, and save a lot of time;
- JMS serializer and its awesome features;
- the HATEOAS project, very nice to unlock the third level of the Richardson maturity model;
- And finaly, a little bit of guzzle to ease communicatio