Still need to improve error handling: NullPointerExceptions are possible
when invoking a call for a non-present list.

Still need some new methods:
- Hourly & Daily dew point
- Hourly & Daily UV index
- Daily morn, day, eve, night, min, max temps, ambient & feels_like
- Dail rain & snow totals

- Renamed `Main` to `Demonstration` and introduced a menu
- Updated JavaDoc to reflect which data sets each method pertains to
- Cleaned up code to extract Longs and Doubles from JSON

- Javadoc
- README