Adding point based data to maps

This PR addresses #8 and #13 

For #13 this is a minimal implementation of adding points to a map. There are a couple of issues and features to be added:

[ ] Make it easy to configure styling of points (currently hard coded for the MVP)
[ ] Add an automated legend like in choropleths
[ ] Add clustering support, cluster by groups if there are different types of icons
[ ] Add automated labeling support from the CSV file

For #8 I've simply added a config in the _data folder to specify the order of the groups and supergroups and then added behavior to _includes/databrowser.html to loop through this configuration array.