Don't include French Guiana in France's coordinates

When we select France in the choropleth world map, French Guiana gets included (see the Northeast corner of South America).

![datamaps](https://cloud.githubusercontent.com/assets/638351/3223437/daeca40a-f022-11e3-920c-65858f339d7d.gif)

I removed the coordinates for French Guiana from the France feature in world.json, created a new feature for French Guiana, ran `topojson world.json -o world.topo.json`, then ran `grunt build`. Please let me know if I missed anything or need to do anything else to make this PR merge-able.