Added syncing of glance image directories

This allows for a true HA glance, without all the complexities
of the existing sync tools.  BT is locked down with a secret,
and we are further locking down our controllers with iptables.
This should be a fairly safe rollout.

Taken mostly from @alop's work [1].

[1] https://github.com/alop/cookbook-image-sync
Merge pull request #204 from blueboxgroup/blueboxgroup/glance-ha

Added syncing of glance image directories