Send the notifications to the Ceilometer for backup service

* Add the notification send-out for create_backup, delete_backup
  and restore_backup.
* Add the progress notification to Swift backup service.

DocImpact

Change-Id: I9835073a39aa8b2ffbec12d84147cce027ff731b
implements-bp: backup-notification
Merge "Send the notifications to the Ceilometer for backup service"