Add metadata to releases

[rplzzz]

Zenodo does its best to infer things like authors and whatnot when it assigns a DOI to a release, but there is only so much it can do. We should probably tidy up the metadata for our latest release. For example, we should probably add Robert G. under the contributors section. I also gave our affiliations as "Pacific Northwest National Laboratory", but we can tweak that if people aren't happy with that. The record can be edited (though I'm not 100% sure by whom, other than me) at: https://zenodo.org/record/821646

In the long run, we can add a .zenodo.json file to do this stuff automatically whenever we create a new release.