Successfully test Omron LED driver

 - Fixed minor command formation bug in led_control_lib.py.

 - Updated ledControl_test.py to perform more advanced test. It now turns LEDs on,
fades groups A, B, and C out, then fades groups 0, 1, and 2 in before
turning all groups off and terminating.

 - Created led_heartbeat_test.py for RPi basic LED heartbeat.