Merge changes I34d7ee3b,I99337ea2,I5c190938,If79073a9,Ie3343681 into qt-qpr1-dev

* changes:
  Reschedule the pre-reboot verification after boot completed.
  Prevent sessions from resuming once boot is completed
  Prevent extra sessions owned by staged install from living across restarts
  Prevent exceptions during staged install from crashing system server
  Prevent exceptions in pre-reboot verification from crashing system server