Automatic merge from submit-queue

Run rbac authorizer from cache

RBAC authorization can be run very effectively out of a cache.  The cache is a normal reflector backed cache (shared informer).

I've split this into three parts:
 1. slim down the authorizer interfaces
 1. boilerplate for adding rbac shared informers and associated listers which conform to the new interfaces
 1. wiring

@liggitt @ericchiang @kubernetes/sig-auth