GPS: add signal to show that a new fix has been acquired

This way if we don't have a current enough position we can wait for a
current fix to be acquired.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

core/gpslocation.h

@@ -59,6 +59,7 @@ private:
 
 signals:
 	void haveSourceChanged();
+	void acquiredPosition();
 
 public slots:
 	void serviceEnable(bool toggle);