director: Minor code cleanup - allow access to auth connection's ostream directly.

director: Reverted previous e178413a905d commit after all - do it a bit differently.

director: Added a new DIRECTOR-LOOKUP command that auth connections can use. The parameters are the same as what auth lookup would receive from auth process. So the idea is that a proxy could do an auth lookup, then forward the reply to director, which would return back the updated reply with the host field added.

director: Lots of fixes. It should be pretty stable now. --HG-- branch : HEAD

Added initial implementation of a director process (for NFS users). There are still some unimplemented features and bugs. Also changing mail server list doesn't yet make sure that other directors won't assign the same user to a different server at the same time. --HG-- branch : HEAD