Support for koji profiles.
    
    This patch is dmach's patch [1] refactored according to mikem's comments [2].
    
    [1] https://lists.fedoraproject.org/pipermail/buildsys/2015-August/004857.html
    [2] https://lists.fedoraproject.org/pipermail/buildsys/2015-October/004900.html
    
    Signed-off-by: Tomas Mlcoch <tmlcoch@redhat.com>