Allow additional/custom filtering of sensitive info in logs/reports

[DavidUnderdown]

It's great that you already filter out obviously sensitive things like the username/password used to connect to the database being preserved. However, we would typically regard things like the fully-qualified domain name of the server as being sensitive too, so it would be great if there was a bit more control over some of the things that go into the report and log, perhaps using a similar mechanism to the other metadata fields such as --export-meta-archiver-contact[=value]