Convergence: send notification when a stack action starts
Convergence: send notification when a stack action starts

Send notification and add event when a stack action is
triggered.

Change-Id: I9596cdffcc0e2f92580bd85dfc6ac6a17c01d120
Partial-Bug: #1512343

dragorosson/heat,cwolferh/heat-scratch,jasondunsmore/heat,openstack/heat,gonzolino/heat,steveb/heat,steveb/heat,jasondunsmore/heat,cwolferh/heat-scratch,openstack/heat,dragorosson/heat,dims/heat,dims/heat,noironetworks/heat,gonzolino/heat,noironetworks/heat