Filtering subcatalog by country or region

[pkerins]

Should be able to include or exclude training or scoring datasets based on region or country, rather than always having to operate on the city basis. Requires modification to catalog itself (as well as all the city-specific catalogs, before or after subdivision of remaining "master" catalog), then can incorporate that into some wrapper & accessor functions so that we don't have to manipulate that catalog directly, unless we want to.