Add notification for live migration

Fix bug 1167759

Currently, if live migration failed, nova compute did not send
notification, this causes other services such as nova-scheduler
to have no chance to do some operations

The fix add notification logic for live_migration like other
VM instance operations such as resize, run instance etc.

Change-Id: Iaf61f5268e07284fd7d69ff331ce3bacd380c02b
Merge "Add notification for live migration"