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 
My original goal here was to make this section each in route:

* more readable and descriptive
* make it DRY so it would be easier to change the strings later, if need be

Adding the constants accomplished the second goal, and I think the scope constant is more descriptive, but the strategy is not more descriptive. As is, it signals "it uses the strategy defined in auth.AUTH_STRATEGY", which doesn't provide much information. Ideally, I think this would be something like `auth.BEARER_TOKEN` because that tells me this request is authenticated with bearer tokens, but Hapi wants "Bearer token" to describe the scheme and not the strategy. Not sure I can win here, but I'm open to suggestions.