Handle GPSDConsumer not existing

In some case GPSDConsumer might not get started, but we might still
attempt to disable GPSD based location. So don't traceback in such case.
Make sure modRana correctly shutdowns on Sailfish OS

For some reason the PyOtherSide atexit handler does not work
on Sailfish OS. Fortunately triggering the shutdown in a
onDestruction handler of the root QML element works fine. .)