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.
Improved docker reload command to wait for etcd to be
up before proceeding. Switched reload to run restart
because it can't reload if it is not guaranteed to be
in running state.
Running etcd in Docker reduces the number of individual file
downloads and services running on the host.
Note: etcd container v3.0.1 moves bindir to /usr/local/bin
Fixes: #298
Matthew Mosesohn