Openstack HA Playbook

* Installs and configures corosync and pacemaker to manage:
 * Floating IP 
 * Neutron L3 Agent Service failover

* Changes startup & shutdown order of corosync & pacemaker rc.d scripts to allow these services to function properly during such events.

* The FQDN of Openstack service endpoints is set to resolve to 127.0.0.1 via /etc/hosts in order to keep each node self-reliant and not cause mass service outages if pacemaker fails to bring up or transfer floating IP on the active node.