Implements Client Management Endpoints

We already had the R of CRUD, this adds the other 3. The 3 new endpoints require an oauth token with the scope `oauth`. Yo dawg, I heard you like oauth?

@rfk r?
@vladikoff you should take a look and see if there's something I've forgotten that the console will need.

fixes #60 
That's exactly how they're used. 401 is used for invalid credentials, 403 is used for credentials that don't have enough permission. If not, thats a bug on my part.