USPi Environment and samples added
sample/makeall did not work on Rasbian wheezy
Multiple mass storage / gamepad devices supported

(Gamepad device status handler still has to get device index)
USB device information provided (to identify devices)

Mass storage sample added

"class" TUSBString added

Changes by Marco Maccaferri:
  Gamepad device supports hat switches
  Gamepad device supports different minimum/maximum for each axis
  Gamepad device uses calulated report size for transfers
Ensure build is done with signed char