[ardrone] Removed all USE_IMU defines from main.c to revert it back to the master version as much as possible while still being able to fly with both ardrones.
Therefore added an empty imu for sdk version and renamed the existing raw version imu. Also adapter the makefile to include the right files.
In the sdk airframe IMU neutrals,sens and signs are added to make it compile. This doesnt affect how the ardrone2-sdk flies. TODO: fill in the imu rates from the api-navdata strukt (not to be confused with the raw-navdata). Test flight with SDK: can take of, but doesnt respond to joystick anymore after taking off. With raw: flies like usual.
Merge branch 'ardrone_to_master' of github.com:RoboticaTUDelft/paparazzi into ardrone_to_master

Conflicts:
	sw/airborne/firmwares/rotorcraft/main.c