Finish writing commands for clearing obstacles

[agausmann]

Once #55 and #11 are done, we need to start testing on various obstacles. We want to be able to clear most of the obstacles during autonomous, minus the sally port and drawbridge (which we are not able to clear at all). At the very least, we want to be able to clear 1 category. Here is a summary of each obstacle:

Category A

Portcullis:

• Move arm to "start portcullis" position
• Drive forward until arm is under portcullis
• Move arm to "lift portcullis" position
• Drive forward 1-2 meters

Cheval de Frise:

• Drive forward to obstacle
• Move arm to "lower cheval" position
• Drive forward 0.5 meters
• Move arm "out of the way" (home?)
• Drive forward 1 meter

Category B

Moat:

• Drive forward (varying speed/direction? requires tuning)

Ramparts:

• Drive forward (requires tuning)

Category C - impossible

Category D

Rock Wall:

• Drive forward (requires tuning)

Rough Terrain:

• Drive forward (requires tuning)

Non-selectable

Low Bar:

• Drive forward a few meters