plumb cni settings

[w9n]

- What I did
Minimize usage of /var binding in containers and simplify cni metadata path.
- How I did it
Let the cni config persist on /var/lib/cni/conf and /var/lib/cni/bin.
then mount share them to their default position in /etc/cni/net.d and /opt/cni/bin in docker, kubelet and hostroot (cri-containerd mounts weave pods HostPath here).
- How to verify it
I run both cluster types.
- Description for the changelog

plumb cni settings

- A picture of a cute animal (not mandatory but encouraged)

[ijc]

Mostly LGTM but clashes with your #27 that I've just merged, please rebase.

Also you need to update yml/bridge.yml with the new config path.

Would be best if you could rebase onto #33 since I'm about to rebase & (hopefully) merge that one too.

[ijc]

#33 is merged so rebase onto master should be sufficient.

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "cni_settings" git@github.com:w9n/kubernetes.git somewhere
$ cd somewhere
$ git rebase -i HEAD~842354109296
editor opens
change each 'pick' to 'edit'
save the file and quit
$ git commit --amend -s --no-edit
$ git rebase --continue # and repeat the amend for each commit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.