Need to add specific command line arguments

[jessehamner]

The NWS doesn't release new forecasts every hour, but it does release new radar images many times an hour. Therefore it makes no sense to retrieve forecasts, area forecast discussions, or current weather observation data on the same schedule as retrieving radar images and alerts data.

The main script should implement docopts such that individually useful data can be retrieved with the temporal granularity that is warranted by the frequency of the data being updated. Then the scheduled execution of the main script could be easily configured to gather data as needed. This move should improve overall performance and avoid wasting both bandwidth and time.