Add PID tunning to debugger class. Potentionmeter read to Mux class. SetPidGain to RobotArm class.
Fix issues with PID debugger.
Update robot arm and debugger to controll two joints at once.
First version of motor speed boost code for low speed motor operation

Adds motor speed boost code in the RobotArm class for low speed motor
operation. Currently has a bug that causes a random long term boost
after and random period of time.
Fix bug in motor speed boost code caused by time overflow.
Change lastPidTime to an unsigned int
Merge branch 'rpi-development' of github.com:gcc-robotics/prometheus into rpi-development
Add command processor for serial commands to arduino code.