First step of removing Mac vs Linux code
Remove the now, no longer needed, UsbLedLinux class
Renamed UsbLedMac to UsbLedGen1 in readiness for UsbLedGen2 (a.k.a. 9xxxxx series Delcom lights)
Added guard around detaching kernel driver.  Only needs to be done once
Removed platform to usbled map
Starting to move usbled instantiation to UsbLedFinder class
Moved platform support error message to finder class
Removed get_usbled method from HudsonBuildLight class
Moved exit hook to turn off lights into UsbLedGen1 class
Moved set_color method to be on the UsbLed class rather than in the HudsonBuildLight
Removed unused imports