storage: re-add and deprecate alarm_connection
storage: re-add and deprecate alarm_connection

This is needed to allow transition from Ceilometer more easily.

Change-Id: Ie39928db56f9632ef949f2bc3b44af48a72e8a6f

openstack/aodh,sileht/aodh,pczerkas/aodh,pczerkas/aodh,sileht/aodh,openstack/aodh