atomic: move to new versioning scheme for ostree
    
    We have decided [1] that we want to have more meaningful versions
    for ostree commits and the resulting images. One way to do this
    is to have the ostree version match the version from the compose ID.
    
    Pungi recently [2] gained support for embedding the label from the
    compose into the ostree commit version. This change takes advantage
    of that work to embed a more meaninful version.
    
    [1] https://pagure.io/atomic-wg/issue/229
    [2] https://pagure.io/pungi/pull-request/592
    
    Signed-off-by: Dusty Mabe <dusty@dustymabe.com>