Udev rules, autosleep, bugfixes

[dputtick]

• Wrote udev rules which ensure that the first usb port will deterministically map to /dev/source_key and the other ports to /dev/dest_key.
• Added lines to init.sh that turn off display autosleep on the hdmi port - resolves #44.
• Added more comments to make the bash scripts easier to understand.
• Split the key detection/mounting and groomer logic into separate bash scripts.
• Removed LED related stuff from this branch of the repo since we don't use it. It can still be found in the old-version branch.

[Rafiot]

Excellent, thanks!