WIP on making an example with some real-life data
Add an example that uses Cosmos' groupBy functionality to compute the top-ten
most frequent values in a given column for the city of Chicago's building
permits.

- Make the return on groupBy be CloseableIterable instead of Iterable
- Auto-close all CloseableIterables when the delegate is exhausted
Format the README with some reasonable line-wraps
Default to loading the entire data set