engine: application touches a file to detect un orderly shutdown

Used to diagnose unexpected engine stop by the notification service.
Previously we used the pid file, buy this solution becomes irrelevant
for systemd.

Change-Id: Ic8de64637299e7932a5a2761c7bb495373c418aa
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=743660
Signed-off-by: Mooli Tayer <mtayer@redhat.com>