Add LED support to the haskell api

Add/Throw a new exception if setting LED fails.
Add new datatype for LED colors
Add FFI wrapper to freenect_set_led
Add setLed call for haskell API.
Fix BlinkRedYellow Code and set setLed/Led(..) to public.

Fix BlinkRedYellow code that uses not an ordered enum integer.
(small exception, see libfreenect.h)

Add setLed and Led(..) to the public module interface Freenect.
Add example programm for switching LED

Add a simple test programm for switching LED.
Merge pull request #6 from ruuns/master

Add support for LED switching