Per-author metadata

It may be useful to generate BibTeX files for each author. Now that we have greatly straightened out author IDs (with [another round of improvements in the pipeline](https://github.com/acl-org/acl-anthology/pull/297)), it would be feasible, with Softconf collaboration, to allow people to add their Anthology author page to their START profiles, which could then be used to pull in their papers automatically in service of reviewer assignment. This idea was mentioned in [Stent & Ji’s NAACL 2018 blog post](https://naacl2018.wordpress.com/2018/01/28/a-review-of-reviewer-assignment-methods/).

Another perhaps more robust option: create a JSON file for each author, listing all the metadata we have for them name variants, Anthology paper IDs organized by year, co-author graph, and so on. This would be the first step in the direction of an API.