Allow tests to run outside tox
Allow tests to run outside tox

When using a test runner outside of tox (for example
using py.test directly against test files, one of several
ways to enable faster and more specific testing)
oslo.messaging.conffixture is not imported and text/base fails
to compile.

This change gets things working and otherwise has no impact.

Change-Id: Ibac6ae0a73aa55522b248a26b9a4b82455f8fce6

MisterPup/Ceilometer-Juno-Extension,pczerkas/aodh,m1093782566/openstack_org_ceilometer,redhat-openstack/ceilometer,fabian4/ceilometer,mathslinux/ceilometer,pkilambi/ceilometer,Juniper/ceilometer,mathslinux/ceilometer,cernops/ceilometer,r-mibu/ceilometer,redhat-openstack/ceilometer,maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,openstack/aodh,idegtiarov/ceilometer,ityaptin/ceilometer,ityaptin/ceilometer,fabian4/ceilometer,idegtiarov/ceilometer,Juniper/ceilometer,luogangyi/Ceilometer-oVirt,maestro-hybrid-cloud/ceilometer,MisterPup/Ceilometer-Juno-Extension,luogangyi/Ceilometer-oVirt,openstack/ceilometer,openstack/aodh,r-mibu/ceilometer,isyippee/ceilometer,sileht/aodh,m1093782566/openstack_org_ceilometer,chungg/aodh,pkilambi/ceilometer,froyobin/ceilometer,eayunstack/ceilometer,isyippee/ceilometer,openstack/ceilometer,cernops/ceilometer,froyobin/ceilometer,chungg/aodh,sileht/aodh,pczerkas/aodh