Fix bug #1075268 - Support multiple notification handlers listening to the same notification type
Fix bug #1075268 - Support multiple notification handlers listening to the same notification type

Change-Id: I4816f494ecee46eec3721160648dabae845edca0

ionrock/designate,cneill/designate,cneill/designate,cneill/designate-testing,openstack/designate,tonyli71/designate,muraliselva10/designate,kiall/designate-py3,melodous/designate,tonyli71/designate,ramsateesh/designate,richm/designate,muraliselva10/designate,ionrock/designate,ramsateesh/designate,muraliselva10/designate,ionrock/designate,ramsateesh/designate,openstack/designate,cneill/designate-testing,kiall/designate-py3,melodous/designate,grahamhayes/designate,melodous/designate,cneill/designate,cneill/designate,kiall/designate-py3,tonyli71/designate,grahamhayes/designate,melodous/designate,cneill/designate,richm/designate,openstack/designate,NeCTAR-RC/designate,kiall/designate-py3,NeCTAR-RC/designate,cneill/designate-testing,kiall/designate-py3,grahamhayes/designate