[test_gps] Improve agps support

* The SUPL api seems very sensitive to the AGPS type
* Get more info about the sattelites
* Check AGPS SUPL connection handling

Signed-off-by: Philippe De Swert <philippe.deswert@jollamobile.com>
Merge pull request #142 from philippedeswert/agps

[test_gps] Improve agps support