Restructure several commands and subsystems to allow for easier usage

Structure
- Create a ToggableSubsytem class that extends Subsystem and handles
  subsystems with two discreet states.
- Create a Toggle Command that switches the state of a
  ToggableSubsystem.
- Create a CommandBase that extends Command and provides default
  implementations for every method in Command.
- Create a OneShotCommand that extends CommandBase and can only be
  executed once.
- Remove the commands that were used before to toggle subsystems.
- Create a Nets class that extends ToggableSubsystem.
- Update RollerArm to use the new ToggableSubsystem