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).

2c07bcf56a36d6e74dc0f5422e89bd61f4d31239 0.8-diverge
1656d4fd71d07aa3a52da89d4daf7723a555e7dd last-google-code-commit