Bz1129462 openstack handle metering

Fix a bug where the Metering Service (Ceilometer) was not appropriately wrapped in the new Openstack Service Delegate construct introduced for Tenant support in ManageIQ.

This also introduces the ability for new Openstack services to be supported without requiring a service wrapper.

https://bugzilla.redhat.com/show_bug.cgi?id=1129462
Well, it's optional in that it's only required on an appliance if the appliance is setup to collect C&U.

I'll add the nil entry to the fallback list.