Tutorial update.
Tutorial update.

AlanJAS/pyusb,rabryan/pyusb,h3nj3/pyusb,h3nj3/pyusb,karlp/pyusb,AlanJAS/pyusb,makerbot/pyusb,kopchik/pyusb,kopchik/pyusb,rabryan/pyusb,karlp/pyusb,makerbot/pyusb,swinman/pyusb,swinman/pyusb