Merge pull request #12927 from nullaus/bug918143-group-notifications

bug 918143(cherry picked from commit 163f47b8ca0c6f9cead75347793d8fc39bfefa59)

Conflicts:
	apps/system/test/marionette/lib/notification.js
	apps/system/test/marionette/notification_test.js
Merge pull request #13077 from nullaus/v1.2

Merge pull request #12927 from nullaus/bug918143-group-notifications