Run as user/group plinth, not www-data.
Rewrite to use lsb init-functions for starting/stopping and output.
Use /bin/sh instead of bash to speed up the boot.
- add exmachina code and test code
- modify plinth.py to listen for shared secret on stdin at start
(if appropriate flag is set) and try to connect to exmachina daemon
- use exmachina to read and set /etc/hostname as a demo
- update plinth init.d script to start exmachina and share keys
- update docs with new deps and run instructions
