Charting in UBIF 2.0

We are using the d3.js library to draw our charts. The plan is to develop charts that resemble those found in this folder in the code base: https://github.com/glenpierce/UBHub/tree/iNaturalist/public/images/charts

Note: these images are slightly out of date as the current specification does not include the target figures as represented here, but instead in the stoplight fashion as described in https://github.com/glenpierce/UBHub/issues/61