Revert "Always assume someoneWasListening when we get invalid notification in emityNotification()"

This reverts commit afc24995c526e6f6ee3d231a21ce21bf08fb69d4.

someoneWasListening is essential for the change recorder and simply
setting this to true if no one was listening breaks it (because no one
will call replayNext).

Conflicts:
	akonadi/monitor_p.cpp