Allow overriding of author information from the additional metadata file

[daveverwer]

The name and link for every displayed author should be able to be overridden by our extra metadata file.

The list of contributors should be custom at this point, and we should replace any automated data with only the names and links in the metadata file. The link may point to any web site, not just their GitHub profile. (Yes, this opens up the possibility of spam, but let's deal with that as it comes up).