Use runit instead of providing init scripts.

Rather than providing init scripts for every distro, I decided to
make use of runit. While this is currently working nicely. I don't
feel it's fully baked yet. I do not want to have to rely on tmux or
screen, so at the moment the only way to control the server is from
the game. I plan to look into using bidirectional pipes, or maybe
even rcon.