Steering controller retune

[jcirce]

The following retunes the steering inner loop and adds functionality to adjust gains over CAN

notes:

• removed -1 on degrees, steering convention is positive right & negative left
• increased kp with some ki, with the higher limits, the response is fast with no overshoot and minimal steady state error.
• added velocity enable so that motor is not pulling current for small amounts of velocity ~ small angle errors