Potential fix for receiver leak problem

The background thread is not stopping listening fast enough and is
resulting in first a receiver leak message followed by a crash when
trying to finally unregister the receiver.

Fix this by adding a registerReceiver to SummaryLoader that will
automatically unregister the receiver on the main thread to ensure
it happens in time.

Change-Id: I0104e929d5505eb53993f6765e4c90120df35cf6
Fixes: 28211606