Simplify use of constants for bmRequestType.

LIBUSB::Call is more or less an internal class. The intended use
of all constants is through LIBUSB:: module.
Merge pull request #2 from larskanis/patch-1

Simplify use of constants for bmRequestType.
New Feature! ws2811/ws2812 pixel support! Adding examples also! Video here! https://vine.co/v/bVPlaKJ1VH3 shows examples/ws2811 scan.rb running ^_^
examples/ws2811.rb sped up animation
Change require path in examples
New Rubygem released: 0.9.2
Added ws2811 example for little strobe light ^_^
updated library to work with latest littlewire revisons
released 0.9.3 with new littlewire prerelease ws2811 compatibility updates
Merge pull request #3 from Bluebie/master

Keep updated ...