Lay down groundwork for registration service.

Let's discuss registration, round 2.
Its common practice in REST to simply post to the resource, implying you're creating a new resource.

As I mention above we really just need to annotate this with @POST and we'll be sticking more closely to REST principles.  The only time we'd really need a path for a simple, definable resource like a User is for GET's and queries.  So something like GET /users/15 would get you a User with an ID of 15.