As the final step, add the `dockerless` tags to all files in the
dockershim. Using `-tags=dockerless` in `go build`, we can compile
kubelet without the dockershim.
Once cadvisor no longer depends on `docker/docker`, compiling with
`-tags=dockerless` should be sufficient to compile the Kubelet w/o a
dependency on `docker/docker`.
This change add a container manager inside the dockershim to move docker daemon
and associated processes to a specified cgroup. The original kubelet container
manager will continue checking the name of the cgroup, so that kubelet know how
to report runtime stats.
