Restore OI to a post-compile-time instance of the class. As the comment notes this is necessary to ensure that the subsystems are initialized *before* OI.

Similarly, remove any references to OI object in subsystems; OI objects should be passed to subsystems from commands.
Restore the TestMotors subsystem/command.

Eventually this will need to use a different joystick/axis/button/etc. but this is still a useful base.