Policy distribution through nova.

Implementing functionality in cobalt to allow distribution of
vmspolicyd policies to all known vms hosts. The client takes a path to
a locally accessible policy file, and the contents of this file is
copied into all the policy definition files on all hosts. The compute
service does so basic validation on the provided definitions before
installing them.

Change-Id: I3506a00b9b65d7df6d0a9f878a2b99d0b5c1bbbf
WIP: Poll

Change-Id: I7c2af7e983a3a87d9125eb4a742e85557f60de62