mod_pubsub_serverinfo: implemented all basic features This commit replaces the earlier proof-of-concept to a solution that: - reports on remotely-connected domains - uses disco/info to detect if those domains opt-in - publishes domain names for remote domains that do so - caches the disco/info response

This module allows sending a message to another MUC room.

    @other-room: hello

The message will appear in the other room as as

    <first-room/You> hello