Kubelet etcd watch skipping indices

The next index to watch should always be current+1 if we got a
response from etcd, but otherwise it should always be current.
Moved the increment into fetchNextState which returns the next
index to watch for (or the same if an error occurs)
Merge pull request #569 from smarterclayton/fix_bad_watch_in_etcd

Kubelet etcd watch skipping indices