Igcs 136 ardrone ftp

** NOT READY TO BE MERGED YET* 

Opening PR so @cnatoli and @andymoe  can follow along and provide feedback if asked.
In order to handle this properly we need to know if we are actually connected to an AR.Drone. We can't assume all MAV_AUTOPILOT_GENRIC types are AR.Drone. Please open a ticket to add a flag to keep track of weather we are talking to an AR.Drone or not.