Add mandatory middleware to proxy pipeline
    
    See bz#1051113, bz#1181126. People keep getting confused about this.
    Although nowadays (after Havana) the code forces mandatory middleware
    anyway, it emits a warning message. Adding the middleware makes that
    message to go away.
    
    In addition, we re-arrange the proxy-server.conf order just a bit,
    to make it match the upstream for easy diffing.