Watch and Get on the same Etcd key.

Kubelet was killing existing pods when creating a new one because new
files were being set as /registry/hosts/<machine>/pods/<id> and
/registry/hosts/<machine>/kubelet.

I'm not entirely sure why we're setting in both places. It seems like /pods/ is for master only use whereas /kubelet is the 'outbound' config for the kubelet to read.
Done. I didn't think that path.Join was much safer in this context?