Configuration to build the docker base image, modular f26 (boltron).
    
    Depends on two other PRs being merged first:
    
    - https://pagure.io/fedora-kickstarts/pull-request/257
    - https://pagure.io/pungi-fedora/pull-request/279
    
    Signed-off-by: Ralph Bean <rbean@redhat.com>