We don't test for `key_setup?` in `wunderground`. Also, if we are testing, this is better:

    if key_setup?
      ForecastIO.api_key = options['api_key']
      lat, long = options['location'].split(',')
      data = ForecastIO.forecast(lat, long)['daily']['data']
      return data
    end

The normal flow of code with `validate_options` ensures that `key_setup?` must be true here, but since its a public method, perhaps we do need the guard?

BTW, is there a coding convention for `return` versus falling though?