Add gear handling subsystem

[jwalthour]

Actuators include (names in 2017 code):

• Face push (ExtendFace)
• Jazz hands (OpenPooper, ClosePooper (don't ask))
• Hat tip (hatTip)

Suggested steps

• [ ] Familiarize yourself with existing subsystems in the 2018 code, like Claw and Wrist, to see how they're structured.
• [ ] Familiarize yourself with the actuators listed above in the 2017 code, using the related names/terms listed in parentheses, and how they were set-up in things like RobotMap
• [ ] Create a GearHandling class based on the structure in the Claw and Wrist classes, but using the content for the actuators listed above from the 2017 code.

[jwalthour]

I think we can safely close this one, as we've started on the 2018 robot. Let me know if anyone thinks we should still add this!