Map showing Council Districts and work order volume would be useful information. Add this.

1. add map to charts.py module that maps work order request volume onto a chloropleth map to show number of work order reqeusts by city council district
2. add a year filter for all or for individual fiscal year (parameter)
3. add a view filter or option to show colorscale by volume or by pct closed on time (parameter)

Start by reading charts.py and tracing how its chart parameters are exposed. Define the map’s district-level work-order volume, fiscal-year selection, and colorscale option for volume or percentage closed on time; the work is done when all three requested controls are available and the map displays the requested district data.

Written by the indexing model from the issue text.