Fix issue #3377999: Activities need to be stopped when sleeping

This is a band-aid over the existing kludgy stopping mechanism
where the semantics of stop are different in the activity manager
than in the clients.

This change is intended to be as unobtrusive as possible, only
impacting the sleep case.  I have a different change that
completely reworks how we stop activities to simply this all
a lot by unifying the semantics between the server and client.
However, it is too late in HC for such an extensive change.  Later
I'll revert this one and put in the better solution.

Change-Id: Id77f2db1ec83469cdd888acb8fbc4679daa7766e