Oauth authentification for third-party application

Let's make Claroline Connect open to third-party application.

It's a first implementation of the Oauth protocol using the [FOSOAuthServerBundle](https://github.com/FriendsOfSymfony/FOSOAuthServerBundle).

All is here to allow third-party application to connect to Claroline for accessing API.

For now there is only one very simple API, getting back all or one badge.
No public API for now.