Don't enable IMU in master branch.
Add IMU ROS message type.
Add imu entry to robot_state.
Add IMU pitch and velocity fields.
Add IMU Medulla driver.
Add IMU Medulla entry to ecat conn.
Merge branch 'master' into medulla_imu

Resolved:
	firmware/atrias2.1/Makefile
Add a slightly modified version of the motor position controller for IMU testing.

This controller will hold the legs downwards (normal to the floor) regardless
of body pitch, the right leg 10 degrees in front of the left.