Watch delivers current state for resourceVersion=0

Allows clients to get the current state without having to execute
a get followed by a watch.  Makes integration with action loops
much cleaner.

Split from #846
It *used* to be a []api.ContainerManifest. I made it into a api.ContainerManifestList. See: https://github.com/GoogleCloudPlatform/kubernetes/blob/71c6e082d497696a9875d62412f22ae9d19d2491/pkg/registry/etcdregistry.go#L113

We should *not* be storing a list of lists in etcd. I had to make the above change in order to make these objects work with api.Decode().