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`.
With CRI, kubelet no longer sets up networking for the pods. The
dockershim package is the rightful owner and the only user of the
newtork package. This change moves the package into dockershim to make
the distinction obvious, and untangles the codebase.
The`network/dns`is kept in the original package since it is only used by
kubelet.
