nova fake libvirt library breaking tests
nova fake libvirt library breaking tests

fixes bug #1074488 Nova libvirt fake library
was updated to include additional 'virtapi' arg
required and our tests do not pass any args to
it therefore breaking them. dansmith recommended
to change fake.FakeDriver to Fake.FakeVirtAPI
which will replicate the old functionality.

Change-Id: Iedcd32cd038c6043d782565312adf5fcba8d9b7a

m1093782566/openstack_org_ceilometer,citrix-openstack-build/ceilometer,NeCTAR-RC/ceilometer,isyippee/ceilometer,sileht/aodh,cernops/ceilometer,shootstar/ctest,Juniper/ceilometer,JioCloud/ceilometer,sileht/aodh,rickerc/ceilometer_audit,NeCTAR-RC/ceilometer,shootstar/ctest,idegtiarov/ceilometer,maestro-hybrid-cloud/ceilometer,pkilambi/ceilometer,r-mibu/ceilometer,openstack/aodh,dreamhost/ceilometer,pczerkas/aodh,rackerlabs/instrumented-ceilometer,maestro-hybrid-cloud/ceilometer,dreamhost/ceilometer,rickerc/ceilometer_audit,rickerc/ceilometer_audit,Juniper/ceilometer,chungg/aodh,openstack/ceilometer,rackerlabs/instrumented-ceilometer,luogangyi/Ceilometer-oVirt,froyobin/ceilometer,openstack/aodh,pczerkas/aodh,chungg/aodh,tanglei528/ceilometer,eayunstack/ceilometer,tanglei528/ceilometer,ityaptin/ceilometer,idegtiarov/ceilometer,eayunstack/ceilometer,m1093782566/openstack_org_ceilometer,fabian4/ceilometer,r-mibu/ceilometer,citrix-openstack-build/ceilometer,JioCloud/ceilometer,mathslinux/ceilometer,redhat-openstack/ceilometer,openstack/ceilometer,froyobin/ceilometer,luogangyi/Ceilometer-oVirt,JioCloud/ceilometer,tanglei528/ceilometer,NeCTAR-RC/ceilometer,ityaptin/ceilometer,rackerlabs/instrumented-ceilometer,citrix-openstack-build/ceilometer,cernops/ceilometer,pkilambi/ceilometer,MisterPup/Ceilometer-Juno-Extension,MisterPup/Ceilometer-Juno-Extension,redhat-openstack/ceilometer,mathslinux/ceilometer,fabian4/ceilometer,isyippee/ceilometer