Let users reset their filter settings to the domain defaults

[rjl]

After enough experimentation with different score thresholds and filter settings, users may at some point just want to revert to the default settings they were assigned when their accounts were created. It would be nice to provide them with a button on their Settings page to offer a "Reset to Defaults" option that would do just that--re-copy the current domain-default policy settings to overwrite their personal settings.