atomic: add code for delta creation of f25 commit
    
    For now we'll define a commit in the N repo to that
    is the last commit from N-1 and we'll generate a static
    delta from that commit to the current release. This is
    so that rebases/upgrades from the previous release are
    much faster.
    
    Signed-off-by: Dusty Mabe <dusty@dustymabe.com>