Allow logged text installs, Branched and Rawhide
    
    This is an attempt to add features desirable for creating
    Taskotron base images. It extends the 'release' handling for
    virt-install images in several ways to allow requesting of
    'branched' and 'rawhide' image creation. It also adds an arg
    to request virt-install image creation run in text mode, not
    graphical mode. Graphical mode is what we always want for
    openQA (so the installed OS doesn't have kernel params intended
    for serial console interaction), but for Taskotron purposes,
    we want the install run in text mode.
    
    This also adds 'branched' to the default JSON file for minimal
    and desktop, as we will want branched versions of these images
    for the critpath update testing workflow to work on Branched
    after Bodhi activation.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>