Implement territory subdivisions

CLDR is adding subdivisions of its territory names e.g. http://www.unicode.org/cldr/charts/32/supplemental/territory_subdivisions.html. Those are pretty cool let's implement them in the plugin.

At the moment, those are considered provisional data items so not included in the JSON files we use. If anyone has urgency, you could always go back and dig up the old XML parsing we originally did and pull from the XML files. I hope CLDR will soon include them in the JSON (maybe [in v32 scheduled to be release mid November 2017](http://cldr.unicode.org/index/downloads/cldr-32)). That would be a lot easier.

Start by reviewing how the plugin currently consumes the CLDR JSON files and the old XML parsing mentioned in the issue. Check whether CLDR v32 or a later release includes territory subdivisions in JSON, then determine how the subdivision data should be exposed by the plugin. Done means territory subdivisions are available from the plugin's localization data.

Written by the indexing model from the issue text.