Add support for service-level annotations

[jacksontj]

Today katalog-sync has annotations on the pods to be synced to consul. It would be nice to support similar annotations on a Service object as well. To implement this we'd need to watch all services with the annotation and sync any local pods that are endpoints of that given service.

[jacksontj]

@ltagliamonte-dd (bringing the convo over here) its on the list but as we don't need this internally it likely won't get prioritized soon. I'd be more than happy to review a PR though if you are (or someone else is) interested :)