mod_pubsub_serverinfo: Update to use mod_server_info (fixes #1841)
...but only for Prosody trunk users, because 0.12 mod_server_contact_info does
not use the new API in mod_server_info.
Introduction
============
This module attempts to sanitize XHTML-IM messages.
It does **not** attempt to sanitize any CSS embedded in `style`
attributes, these are instead stripped by default.
Configuration
=============
Option Type Default
------------------------ --------- ---------
`strip_xhtml_style` boolean `true`
`bounce_invalid_xhtml` boolean `false`