We were using prosody,util.json and cjson at the same time, but the latter is more performant.
Adds some error handling which were missing with the prosody util json one.
* feat: Adds detection of occupants with no connection.
We saw recently two occasions with rooms with participants but no prosody.full_sessions for those participants and when everyone leaves the meeting it never ends.
* squash: Updates counting.
* new prosody module to report census of all rooms
* changed to use util to check if it's a test room
* improved docs
* more doc improvements
* updated to use muc_domain_prefix
* facepalm
