Fixed unwanted reboot every 5 Minutes after -n flash

The error only occurs if there isn't any network connection.
Fixes #23
Also added prevention for applying empty coordinates.

Signed-off-by: Jan Kraus <mayosemmel@gmail.com>
Reviewed-by: Tobias Klaus <tk+ff@meskal.net>
Reviewed-by: Tim Niemeyer <tim@tn-x.org>