Change facility for audit messages written to syslog

When writing the log to syslog, you have the ability to change the facility level for the messages written (with the syslogFacility config option).

When writing the audit log to syslog, there is no option to change the facility. All messages are written to "user" at "info" level severity.

Being able to change the facility would allow users to write audit messages to other syslog destinations.