Update twoweek script to perform release from updates compose
    
    We are now building AH nightly artifacts during bodhi-updates
    run and will be using same for twoweek release.
    
    Example link for one of the updates compose run -
    https://kojipkgs.fedoraproject.org/compose/updates/Fedora-28-updates-20180816.1/
    
    Signed-off-by: Sinny Kumari <sinny@redhat.com>