* first pass at mod_muc_domain open source plus example

* doc - prosody config and config.js examples for mapper

Jitsi Meet doesn't seem to work with c2s_require_encryption set to true.
c2s_require_encryption is false by default. However it is possible that
in some Prosody configurations it is overriden by a global config to be
true. In that case Jitsi Meet might not work out-of-box. So let's set it
explicitly to be sure it is correct.