NeoGpsPlugin - use "gpspipe -r" instead of "cat /dev/ttyO1".

This allows us to have multiple GPS clients at the same time.
Specifically, to have NeronGPS running on the GTA04, and also using
gpspipe to export the GPS NMEA stream over Bluetooth.

(An alternative approach is to use QGpsdWhereabouts instead of
NeoGpsPlugin, but this doesn't work because the QGpsdWhereabouts code
assumes the old GPSD protocol which has now been replaced by JSON.  To
use QGpsdWhereabouts successfully, that code would need updating for
the new protocol, probably by using libgps.

Using "gpspipe -r" at the bottom of NeoGpsPlugin should be equally
effective, and doesn't require such a complex code change.)