Merge pull request #1 from emackey/tweak-d3cs

Tweak d3cs demo
Updated geocode.py to override country names and/or the row to select for the geocoding result.  This fixes the issue where a handful of countries could not be geocoded as well as the pile of countries that were mistakenly geocoded to France.
Added functionality to highlight country in d3 chart when mousing over bar in cesium.  TODO: still need to handle highlights initiated from d3 chart.