mod_delegation: use clean_xmlns to remove jabber:client namespace from node: for the same reason as in mod_privilege, `jabber:client` namespace is removed with the clean_xmlns method coming from there. Furthermore, the forwarded <iq> stanza use the `jabber:client` xmlns while the stanza may come from a component with e.g. `jabber:component:accept` xmlns, this can lead to inconsistencies between the <iq> stanza and children (like <error> element).

Introduction
============

This module checks the IP address of newly registered users against a
DNS block list. If a positive match is found, it gets logged.

Configuration
=============

  Option              Type     Default
  ------------------- -------- ------------
  registration\_rbl   string   *Required*