Ensure support of OAuth2 Token when using the REST API

In the context of a REST based Web Application, we expect the servers to be stateless in order to allow flexible load-balancing and Scale out / Scale down.

Some of the default Nuxeo Authentication mechanisms can depend on the HTTP session (like form based that uses Cookies) : this is something we want to fix.

A much better solution than using Basic Auth is to use a token system.
This is what we do with Drive and Nuxeo Token.

In order to make this more generic we need to :

• ensure the Nuxeo Server can be an OAuth 2 Token provider
• ensure that the Nuxeo client libraries can handle that