Fix bodhi tag settings for beta freeze and final.
    
    At beta freeze we want the 'stable' tag to be the base repo,
    since updates does not exist then. We want bodhi to tag stable
    updates into the base repo.
    
    At final once we are go, we want to tell bodhi to use updates for the
    stable tag since thats when we populate the updates repo and all future
    updates should go there instead of the base repo (which is done).
    
    Signed-off-by: Kevin Fenzi <kevin@scrye.com>