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