Maps are missing several countries

Pygal's maps module seems to have an interesting ad-hoc selection of countries represented on the map. I've found several that are missing:

* Qatar
* Grenada
* Saint Kitts and Nevis
* Saint Lucia
* Barbados
* Federated States of Micronesia
* Bahamas
* Trinidad and Tobago

Ideally pygal should support rendering the standard list of countries from ISO 3166, and use the country abbreviations standardized in ISO3166-1 alpha-2.

Start by locating Pygal's maps module and its existing country definitions. Compare the current selection with ISO 3166-1 and its alpha-2 abbreviations, including the countries listed here. Done means the standard country list is supported and the listed countries render correctly on maps.

Written by the indexing model from the issue text.