feat(contrib/coreos/user-data): create Deis motd

With the upgrade to CoreOS 310.0.0 in #911, the CoreOS motd
lists failed units, 3 of which we expect to be failed (since
we are stopping the reboot manager service). It probably
makes sense for us to manage our own MOTD anyway, with Deis
support information.

This commit works for both CoreOS 298.0.0 and CoreOS 310.0.0.
chore(Vagrantfile): update to CoreOS 310.1.0

Necessary to bump like this until we can reliably switch back
to the alpha release (see #928).
feat(contrib): add CoreOS flair to motd
Merge pull request #937 from deis/coreos-310.1.0

chore(Vagrantfile): update to CoreOS 310.1.0
Merge pull request #926 from deis/deis-motd

feat(contrib/coreos/user-data): create Deis motd
feat(controller): add Domain model

This is added in the API with 2 new URLS

GET /apps/{app}/domains to retrieve the list of the domains
POST /apps/{app}/domains/{domain} to create a new domain.

The CLI is adapted to make use of this new API.