Rackspace - Switch to CoreOS for standard cluster

The Rackspace setup for Kubernetes now leverages CoreOS instead of Ubuntu. We've dropped Salt completely for the cluster.

This doesn't include the updated release scripts so I've left those in the icebox for now.
Totally agree. We'll work on iterating these little scripts to make them more robust. I wonder if building smaller 3rd party Go binaries would be the best course of action. Thoughts?