mod_http_oauth2: Disable CORS for authorization endpoint Per recommendation in draft-ietf-oauth-security-topics-23 Hopefully it is enough to return an error status, since mod_http will add CORS headers from a handler with higher priority, even for OPTIONS.

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.