Add country capital coords

[kpachbiu88]

Use case for the feature

Can you add country capital's coords in the package?

Examples or links

http://techslides.com/demos/country-capitals.json
https://github.com/Ginden/capitals/
http://techslides.com/list-of-countries-and-capitals

[dmythro]

Thanks!
Plan to gather some cities and geo data as additional imports, maybe as a separate module to keep main one small.