MATE: drop colord exclusion (required by foomatic)
    
    foomatic requires colord. Before dnf-3.5.1-2.fc30, this meant
    foomatic was being silently excluded from MATE images. Now it
    means they fail to compose. Let's drop the exclusion so the
    images compose again. If the MATE maintainers want to reduce
    size, they will have to explicitly exclude foomatic (and be OK
    with doing so, as it probably breaks printing).
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>