Create gimbal and science controller modules

[cindyli-13]

Create controller modules for science and gimbal. These would bundle all actuator controller logic into app-specific modules. You should be familiar with the actuator controller libraries before taking on this task. Make sure to develop off of the app-structure-redesign branch.

This task can be broken down into separate tasks per app if needed.

Prerequisite: #382 is merged.

See confluence for project outline: https://wiki.uwaterloo.ca/display/UWRT/FW+Rover+Apps+Structure