container: add aarch64 and ppc64le to what gets built
    
    Also note the change of the url for the "release day" install tree
    /yum repository. We use the pungi locations rather then the public
    urls because we don't have to account for primary vs secondary
    architectures in the URL.
    
    Signed-off-by: Dusty Mabe <dusty@dustymabe.com>