atomic, cloud, docker: correct fedmsgs and bail on fail
    
    These changes bring the post-release compose scripts into line
    with the pre-release ones in a couple of ways. Firstly, they
    should now include the compose ID in fedmsgs sent after the
    compose completes. Secondly, they will skip all post-compose
    tasks (rsyncing and sending 'compose.complete' fedmsgs, and
    sending out mail reports although that's commented out anyway)
    when the compose fails. As part of this, we correct the
    NEWCOMPOSE_ID discovery for these composes.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>