Added provisioner for Deis on DigitalOcean

As DO does not support CoreOS we deploy CoreOS on top of Debian 7.0 x64 using kexec on boot to
switch to the CoreOS kernel and initrd. The state filesystem is a loop mounted btrfs.

The CoreOS bootstrapping is heavily based on Levi Aul's code:

  https://gist.github.com/tsutsu/490f35f48897df0f5173