Kill webob requirement and move expirer to proxy
    
    This turned out to be more involved. The object-expirer had wrong
    config file. In RHOS we got away with adding a pipeline to the
    object server. But as it turns out the proper way to do it is to
    supply it with its own config. The daemon then loads it twice:
    as a daemon and when InternalClient is instantiated. Fine. But
    how create instance'd config for SAIO? There is no special directory
    like /etc/object-server into which to drop instances of expirer.conf.
    For now we nix that option (it is still better than the nonworkable
    config we shipped up to now).
    
    You cannot yet get rid of python-webob on your nodes, because for
    some unfathomable reason, python-keystone requires it, and we require
    python-keystone even on the nodes. This needs fixing next time around.