Make app work in the background

[qtrandev]

If the app is in the background, the process terminates and new data is not refreshed. We need to look at options to allow it to run in the background.

This is most apparent when tracking the GPS Tracker https://github.com/herrdragon/busTrackingGps where every position is logged. When other apps are in the foreground, the history is lost when returning to the Transit Tracker app.