Refine or rewrite EPAS interface

[wheitman]

Problem

Current EPAS interface untouched since Demo 1 this summer. Likely in need of refinement or redo.

Solution

Refine or rewrite EPAS interface, possibly as part of new "TBS" package. A rewrite of CAN interface code may be necessary. The interface should subsribe to "Effort" messages (really just wrapped float values) on the /command/steering topic. These messages will be float values from -1.0 (full left) to +1.0 (full right).

Success condition

The interface subscribes to "Effort" messages on the command/steering topic, using the above format, and connects with our EPAS system to actuate the steering wheel.