Import the api opt group in gabbi fixture
Import the api opt group in gabbi fixture

Without this the later overrides will fail when using the tox
-egabbi target (in the other tests the group is imported elsewhere).

Change-Id: I7ac08c08fe0ec496d93381a9f6ea88762740c278

ityaptin/ceilometer,fabian4/ceilometer,eayunstack/ceilometer,ityaptin/ceilometer,redhat-openstack/ceilometer,mathslinux/ceilometer,isyippee/ceilometer,isyippee/ceilometer,maestro-hybrid-cloud/ceilometer,fabian4/ceilometer,idegtiarov/ceilometer,redhat-openstack/ceilometer,cernops/ceilometer,openstack/ceilometer,idegtiarov/ceilometer,maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,cernops/ceilometer,openstack/ceilometer,mathslinux/ceilometer