Wakelocks held by a client not released if client quits/crashes

[Gerry Boland]

While testing:
https://code.launchpad.net/~gerboland/qtmir/acquire-wakelock/+merge/245942
which acquires a wakelock to ensure app management tasks complete ok, I noticed that the only time a wakelock is actually released is if the client itself explicitly releases it.

If the powerd client crashes, or fails to explicitly release the wakelock itself on exit, the wakelock will be held perpetually.

Suggest that Powerd listens for dbus disconnect signals of clients that acquire a wakelock, and release the wakelock automatically, to robustify against bad clients.