[navstik] Added a new board

Navstik STM32F4 autopilot.
This has the basic support for all the sensors and outputs most autopilots have. Still having issues with the i2c at boot, but seems to be a problem with STM32F4 autopilots.

https://wiki.paparazziuav.org/wiki/NavStik
http://www.navstik.org
Partly, but I will make a seperate pull request for it so we can make sure it works on every board. Together with the editted values on top this should fix most of the binding problems.