Transfer classification codes

[tmorrell]

Classification codes should be mapped to their actual words and then transferred to subjects https://authors.caltech.edu/116782/

Or maybe just create a custom field and copy over the text.

[rsdoiel]

I've done a first pass at getting unique classification_code values from EPrints' CaltechAUTHORS. The line count is 10391. There are visually obvious variations that need to be consolidated and while the numeric values are often delimited by parenthesis it is not always the case. Additionally the ordering of the text label versus number varies.

I'll upload the raw tab delimited file to Confluence as well as my first pass at unique codes.