This patch follows the CoreOS guidance for kubernetes:
https://coreos.com/kubernetes/docs/latest/getting-started.html
CoreOS doesn't support multi-part mime user-data, so we cannot pack
multiple scripts into one (which we did in Atomic). The major work of
this patch is to wrap each cloud-init script with a systemd unit,
which will be executed one-by-one at the first boot.
Note that this patch only enable a basic CoreOS support. Advanced
features (i.e. TLS, Cinder volume, HA, external load balancing) are
not included. These features need to be ported from Atomic as a
future work.
Partially-Implements: blueprint coreos-k8s-bay
Change-Id: Ib6fe76718ac9b198e0aae57618d3edd98792f15d
dc1eacee60