This commit imports the latest development focus from the Charmer team
working to deliver Kubernetes charms with Juju.

Notable Changes:

- The charm is now assembled from layers in $JUJU_ROOT/layers
- Prior, the juju provider would compile and fat-pack the charms, this
  new approach delivers the entirety of Kubernetes via hyperkube.
- Adds Kubedns as part of `cluster/kube-up.sh` and verification
- Removes the hard-coded port 8080 for the Kubernetes Master
- Includes TLS validation
- Validates kubernetes config from leader charm
- Targets Juju 2.0 commands