Add pkgname helper
    
    Fixes https://pagure.io/fedora-packager/issue/162
    
    Suggestion by Adam in https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/message/N444O6WJKADAQN77A4Y5KNBUH2543LAD/
    
    Signed-off-by: Miro Hrončok <miro@hroncok.cz>
    
    Consider this script public domain, hence the license of fedora-packager is not affected.