This basically is the GeoClue2 client functionality a normal application also
uses. We request the current location and subscribe to updates on it.
Only activated when the users does a left click on the gadget so we do not
run always run it in the background. The received information will be displayed
in a popup in a following commit.
This implements an GeoClue2 agents which gets called whenever an application
tries to access the location resource. It allows the user to allow or deny
this resource to the application.