configurable VM name prefix for oVirt

Change-Id: Ie032de0756f2aca2f0e307098fd10b6a4ff68c70
allow multiple oVirt data centers per lab controller

Change-Id: I070a093bdc7ca0973449f6f1fad8c260535bc64d
Merge changes I070a093b,Ie032de07 into develop

* changes:
  allow multiple oVirt data centers per lab controller
  configurable VM name prefix for oVirt