mod_muc_ping: Implements the Server Optimization part of XEP-0410: MUC Self-Ping
Also see #1220
This module implements the [ServerOptimization](https://xmpp.org/extensions/xep-0410.html#serveroptimization)part of [XEP-0410: MUC Self-Ping]It should work with Prosody up until 0.10.x.