Create species index files

[waldoj]

We've got one file per species for fish and one file per species for game—now we need indices to be able to find them. Devise an index.json (or whatever it should be called) structure that can provide basic metadata about the listed species and provide the URL for each file.

[waldoj]

Seems like we'd want the name, the taxonomy, and the filename. Nothing more is obviously useful just now, so I'll start with that.