Add AVRStudio 4 project files to the LowLevel Device mode demos.

Demos/Device/LowLevel/AudioInput/AudioInput.aps

Demos/Device/LowLevel/AudioOutput/AudioOutput.aps

...s/Device/LowLevel/DualVirtualSerial/DualVirtualSerial.aps

Demos/Device/LowLevel/GenericHID/GenericHID.aps

Demos/Device/LowLevel/Joystick/Joystick.aps

Demos/Device/LowLevel/Keyboard/Keyboard.aps

Demos/Device/LowLevel/KeyboardMouse/KeyboardMouse.aps

Demos/Device/LowLevel/MIDI/MIDI.aps

Demos/Device/LowLevel/MassStorage/MassStorage.aps

Demos/Device/LowLevel/Mouse/Mouse.aps

Demos/Device/LowLevel/RNDISEthernet/RNDISEthernet.aps

Demos/Device/LowLevel/VirtualSerial/VirtualSerial.aps

LUFA.pnproj