WIP - Replace Kubelet etcd watching with an API

This replaces Kubelet config loading with a new API resource type
/minionPods which returns an api.PodList (and resourceversion)
for a given minion.  It depends on Watch to inform of new changes,
and adds a change to Watch to deliver the current state of keys when
resourceVersion=0 (not truly required, but makes all clients easier
to use).

Need some feedback on a few things

* changes to watch for resourceVersion=0 case
* how to model parent-child resources in the API
* is api.PodList the right API?
* usage of field selector (and selector introspection)

If the structure makes sense I'll add pulls for the various pieces.

@lavalamp / @thockin