Handle Savanna service availability in tempest

Change-Id: I51300304655803f114d3bb911086cd88aa09638f
Remove powervm nova virt driver support

The powervm virt driver was removed from nova in a
recent change. This functionality is no longer needed in
devstack.

Change-Id: Iec620938a8cce63e0830fc7b9e9a679b361b4389
Merge "Handle Savanna service availability in tempest"
Merge "Remove powervm nova virt driver support"