Add heat auth_encryption_key handling

* Heat auth_encryption_key now readed from nailgun
via osnailyfacter and it should be used for heat-engine
instances in cloud.
* Disabled start-up and run via pacemaker in case
of HA mode for heat-engine.

Change-Id: Icc65f5316762421f1477e32fbd9c3f7071f0a2aa
Related-Bug: #1387345
Merge "Add heat auth_encryption_key handling"