Added possibility to switch sticks
[ardrone2] merge remaining ardrone2 support

closes #396
Merge pull request #440 from EwoudSmeur/switch_sticks

Added possibility to switch sticks

The reason for this commit is that the sticks in rate control are 'quadcopter sticks'.
This is because the default (IMU_TO_BODY) configuration is hover.
The only way to get the sticks naturally right is to have the BODY_TO_IMU
orientation as airplane.
The easier way is to just switch roll and yaw when in rate control,
if the user defined this in his airframe of course.
Merge branch 'master' of git://github.com/paparazzi/paparazzi into samara