Scrape enhanced metadata from BHL

## Description

The Biodiversity History Library (BHL) is great at coopting OL/IA data & metadata without credit, but in some cases they've provided enhanced metadata, so we should "steal" that back.

As an example for the work [Die nordischen Schizopoden](https://openlibrary.org/works/OL13699252W), they had a more complete name for author [Carl Zimmer](https://openlibrary.org/authors/OL6552791A), as well as birth and death dates, allowing the author to be disambiguated from the more popular modern science writer [Carl Zimmer](https://openlibrary.org/authors/OL394581A/Carl_Zimmer)

Because they intentionally obscure the link to the original, this will require going from BHL to IA to OL, but should result in some quantity (unclear how much) of higher quality metadata.

This is related something [mentioned](https://github.com/internetarchive/openlibrary/issues/845#issuecomment-372203711) by @GerardMeijssen a while ago.

Another possible source would be to mine Wikidata property [BHL creator ID](https://www.wikidata.org/wiki/Property:P4081) with the expectation that they are all OL authors.