Log4j or commons-logging integration for the FileLog

I am not sure this is part of 1.3 but I don't think so.

It would be nice if the FileStore class uses commons-logging, log4j or slf4j for outputing the message log to a file. This way we could manage the log files the same way we manage our application logs. For example, it would be interesting in a production environment to be able to use a DailyRollingFileAppender to prevent the file from growing too much. We would also benefit from all formatting options such as timestamps in the platform timezone that are easier to read than the time in the header of the message (which may be in a different timezone depending on the other party).