store history of configs and changes
During a discussion today it occurred to me that there will be situations under which we'll be a lot happier if we can see the history of configuration changes for a given daemon. It shouldn't be too hard to track on the monitors and OSDs; coming up with something appropriate for the MDS (without its own disk space) will take a little more work.
Simple solution: dump the config on every startup and after every change. More complicated tracking is of course possible.