Explicitly ask for py2 dependencies in py2 packages
    
    In future default package names can start to pointing to py3 instead of
    py2. We have to explicitly ask for python2-* and python3-* packages.
    
    This commit changes only dependencies that are available in both F25 and
    F26
    
    https://pagure.io/freeipa/issue/4985
    
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>