This moves a few things around. Namely centos/fedora-rdo-base becomes
centos/rdo/base
fedora/rdo/base

I have also separated out RHEL.

Moves the current scripts in "base" to a "common" folder common to all
images and then recreates the appropriate links to allow all the
containers to build the same way they did before.

This removes all .buildconfs in the system (though they are still usable)

Partially Implements: blueprint refactor-base-image-layout

Co-Authored-By: Martin André <martin.andre@kvhasia.com>
Change-Id: Id63eac1eb9893ceb775c28bf22842dede85c214a