Fix #80: Add Geoclue2 location provider

This simply runs a GLib main loop when the location is requested
and tries to get the location from GeoClue2. We need to run a
main loop since the location is not immediately available, instead
it becomes available through a signal.
contrib: Update RPM spec to use GeoClue2
Merge branch 'geoclue2-provider'

Add GeoClue2 location provider