mod_sasl2: Pull user-agent info into sasl_handler for later reference It may be of interest to post-auth things. Putting it on the session was another option considered, but that seemed unnecessary overhead for something that might be rarely used. sasl_handler is cleared after successful authentication.

This module produces more detailed HTTP logs for Prosodys built-in HTTP
server. The format is similar to that of Apache and go into Prosodys
normal logs at the `info` level.