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 
Yeah, I think switching these constants would also improve readability, e.g.,

`server.auth.strategy(OAUTH_AUTH_STRATEGY, OAUTH_MANAGEMENT_SCOPE)`

but I may have gotten the order wrong. :)