Forecast

This is the implementation of the Forecast Reminder CYOA exercise.
The code is in event_system/forecast_worker

This will show the forecast for the location of Chicago and allows users to register and get forecast information for their own city. The information is updated every hour from the NWS service using their Restful XML API and current weather is pulled from the specific weather station. The data is stored locally for easy access.

The application supports emailing users the forecast in the morning with the current conditions. This allows the user get update by email.

The forecast can be retrieved in JSON for current and past forecasts using the following calls
```
/forecast/index.json
/forecast/index.json?start_time=YYYY-MM-DD
```
Isn't nil implicit here? This is a strange construction.