Update pdns auth init script so it works on wheezy

insserv would complain:
insserv: There is a loop at service pdns if started
insserv: There is a loop between service pdns and mountall if started
insserv: There is a loop between service pdns and mountall-bootclean if started
insserv: Starting rsync depends on pdns and therefore on system facility `$all' which can not be true!