The centos-minimal approach of using rinse does not, it turns out, work
on centos. That's a bummer. It's also rather heavyweight. Instead, with
minor machinations, we can just use yum itself pointed at a chroot.
Also adding fedora-minimal element which creates a fedora image using
the new yum-minimal approach.
Co-Authored-By: Gregory Haynes <greg@greghaynes.net>
Change-Id: I026fd9d323e786dae5bb67824c6501067e1ceaa3
