rkt WIP rpm for CentOS 7 available for people brave enough to test. Throwaway envs preferred.

- IMPORTANT: systemd 222 working on CentOS 7 but it can *ONLY* start filesystems under /, so it goes into recovery mode when /home is a separate partition. Works fine otherwise. Swap doesn't start either but guess it's not that big a deal atm. For details see: https://github.com/coreos/rkt/issues/1305#issuecomment-247111744 . Any help on fixing this welcome :)

- rkt koji URL: https://cbs.centos.org/koji/buildinfo?buildID=12327

- Easy way to fetch this: https://wiki.centos.org/Cloud/rkt?action=show

Let me know..