mod_http_index: Hide http apps that haven't set a title by default This setting was meant to default to this but by some mistake defaulted to true. Apps that haven't set a title might not be meant to be user facing, so hiding them makes sense.

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.