Preliminary GPS support

The latest firmware in the AR.Drone supports the "Flight Recorder" addon which gives GPS support.

Parrot have not updated their API documentation yet but @fvantienen somehow worked out some of the details on the Paparazzi project: https://github.com/paparazzi/paparazzi/pull/463

A lot of the values are untested/unknown, but latitude and longitude is working correctly, so I was able to hack together logging of the drones position on a google map:

![rs8gsv0](https://f.cloud.github.com/assets/1060/1195315/660363d0-2495-11e3-9bab-8e2a7637e7ff.jpg)

This branch is still a work in progress, likely don't want to merge it just yet, will be adding some convenience methods for checking if GPS is attached shortly as well.