Nearly the last stage of source all components to containers.
Kubectl will be called from hyperkube image.
Remaining tasks:
* Move kube_version variable to kubernetes/preinstall
* Drop placeholder download.nothing requirement
kubelet via docker
kube-apiserver as a static pod
Fixed etcd service start to be more tolerant of slow start.
Workaround for kube_version to stay in download role, but not
download an files by creating a new "nothing" download entry.
