Remove outdated AVRStudio project files from demos, projects, bootloaders. Fix makefiles of ClassDriver device demos.

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

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.