Allow Kube proxy to watch for service/endpoint changes

Expose `GET /endpoints/<serviceName>`.  Allow watch on endpoints and with services with `fields=Name%3D<serviceName>`
It currently is a circular dependency between endpoints and service.  The service watch sets endpoints via the service registry object.  Splitting those is probably valuable (esp. if endpoints are settable via the UI) but that requires a bigger change to the endpoints watcher loop.  Once they're split, endpoints and services would be in disjoint repositories and the service-controller would keep them in sync.  I'll add a TODO