Stop using release `version` attribute, just use the compose ID
    
    In several places we combined the fedfind `dist` and `version`
    to identify a compose, which is a bit silly because it basically
    just gives you back the compose ID, except in cases where it's a
    bit broken because of how it's...parsed out of the compose ID.
    I'll fix that in fedfind, but it's still silly to use two things
    that are basically 'the two elements of the compose ID' instead
    of just *using the compose ID*. So let's do that instead.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>