Use openstack.common Nova rpc modules.

Nova still supports the nova.rpc locations but they are old school.

Since Nova I9c2f6bdbe8cd0c44417f75284131dbf3c126d1dd (in Jun 2012)
Nova has prefered the use of the openstack common (oslo) drivers
directly.

Change-Id: I6d2ad7584c6b3a30509ae9e1a360e5f53a49448b
Merge "Use openstack.common Nova rpc modules."