Fixed import issue preventing firmware to compile

You'll probably have to apply this to the other firmware files. Wprogram.h and Wconstants.h have been renamed to Arduino.h as of Arduino 1.0. If you try to compile in the Arduino IDE you are thrown something similar to this:

/libraries/JArduino/JArduino.cpp:20:22: error: WProgram.h: No such file or directory