Add gripper subsystem

[TheConverseEngineer]

This one is super straight-forward, it just needs a few methods:

openClaw();
closeClaw();
openRightClaw();
openLeftClaw();
closeRightClaw();
closeLeftClaw();

Note that the first two methods should apply to both claws. Also note that the hs-65MG servos have a weird PWM range (610-2360μsec), so this will have to be accounted for in code.