Created an example upstart(8) configuration.

The example config presupposes that alicorn is installed in a virtualenv in
`/opt/alicorn`, that there is a user and group named `alicorn`, with
permissions in `/srv/alicorn`, and that there is a configuration file in
`/etc/alicorn.conf`. The bot is rigged to start once networking is up, and to
stop before networking goes away.

I've included a safety net `respawn` stanza; if, for some reason, the bot
exits abruptly, it'll be restarted -- but if it does so more than five times
in the same minute, it'll stop being restarted, to avoid wasting immense
amounts of CPU time looping over bot startup.
Added an example upstart script.

This upstart script is designed for Ubuntu Server, and works to start alicorn
on boot.

Init is dead; long live upstart.