Add initial init scripts library, including systemd, sysvinit, upstart, and openrc
Update hack/make/ubuntu to make less ubuntu-centric packages, to fix the issue of deleting the docker group on every upgrade, to use the new init library scripts for upstart and sysvinit, and to include the dependency on iptables
Merge pull request #2226 from tianon/init

Add initial init scripts library and better/safer Ubuntu packaging that works for Debian, too