Consider support for other init systems

It would be useful to have things like eudev and elogind packaged so that people can use other init systems. The current udev is part of systemd so they'd need options like eudev as part of switching out init systems.

https://trisquel.info/en/forum/how-hard-it-change-init-automatically-remixing-trisquel-live has a conversation showing what they needed to remove because some things needed udev, and are broken with going only with upstart.