Allow keyboard to wake computer from sleep

[DDRBoxman]

Pull request for @tulth 's diff file in issue #21

[squarefrog]

Tried this on my fork, works well with OS X! 👍

[wobbol]

This is a hack. Upstream(tmk) would not be a smart guy to merge this.

A cursory glance at the LUFA library docs tells me that USB_DeviceState holds one of enum USB_Device_States_t of which DEVICE_STATE_Configured is a member.

DEVICE_STATE_Configured roughly means the device has been enumerated and is ready.

In english I read power_down(uinit8_t) as:

• call power_down
• check if device is working if so do nothing else,
• preform low level power down bit twiddling

I do not understand this logic. If anyone has leads on this I would be gad to hear them.