Remove old OTG demo directory with useless TestApp demo. Add new DualRole directory with new Class Driver powered Mouse dual role demonstration application showing a dual role device using the HID host/device Class drivers.

Move new Class Driver powered demos to a new ClassDriver subdirectory, re-add old low level demos to a LowLevel subdirectory.

Moved out each demos' functionality library files (e.g. Ring Buffer library) to /Lib directories for a better directory structure.

Seperated out OTG, Device and Host mode demos into seperate folders for clarity. Adjusted makefiles so that the path to the LUFA library can be set in one place.