mod_rest: Use logger of HTTP request in trunk In Prosody trunk rev c975dafa4303 each HTTP request gained its own log sink, to make it easy to log things related to each request and group those messages. Especially where async is used, spreading the request and response apart as mod_rest does with iq stanzas, this grouped logging should help find related messages.

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.