Add blue-green deployment as a feature request
Add blue-green deployment as a feature request

The feature is required by some field engineers.

Change-Id: I4e38c10fac377853bbd38beb194d23e5a43c46f7

openstack/senlin,tengqm/senlin-container,tengqm/senlin-container,openstack/senlin,openstack/senlin,stackforge/senlin,stackforge/senlin