Add support for polling a Kubernetes Master server

This PR adds support for polling a Kubernetes master server and adding new Kubernetes services as SkyDNS A records.  SRV records are also resolved with appropriate port numbers.

This support is rudimentary, and needs some refactoring, especially if we intend to support more backends in the future.
I'm confused by the first line of this comment and then again by the second line? If not sure, remove it and see what breaks?