mod_client_management: Include software version in table (when known) Showing software versions could be useful for statistical reasons, e.g. determining how quickly (or not) users upgrade, but most importantly for revoking vulnerable clients versions in case of a security issue.

This module writes out a traceback to `traceback.txt` in Prosodys data
directory (see `prosodyctl about`) when the signal `SIGUSR1` is
received. This is useful when debugging seemingly frozen instances in
case it is stuck in Lua code.