Add logos

[cbizon]

Can we add logos (or urls for logos) to the metadata and display on our sources? We may also want to have some logos displayed in footers for various contributing data sets.

[karafecho]

Please see the issue I posted to #154, which is related to your issue, but different, and in my mind, higher priority.

Also note that I don't think we should attempt to use logos for knowledge sources anywhere, as they are usually copyrighted.

[cbizon]

It would require asking for permission, but most folks want to get their stuff out there, so I bet most folks would give it.