Use puts_P() and printf_P() instead of the normal variants where possible in the Host mode Class Driver demos.

Removed accidental reference to the incomplete MIDI class bootloader in the Bootloader folder makefile.

Removed mostly useless "TestApp" demo, as it was mainly useful only for checking for sytax errors in the library.

MIDI device demos now receive MIDI events from the host and display note ON messages via the board LEDs.

Added beginnings of a MIDI class bootloader.