Constants for WeatherViewerActivity setup.
Implemented WeatherViewerActivity's onCreate method.
Implemented WeatherViewerActivity's lifecycle method.
Implemented citiesListChangeListener.
Implemented WeatherViewer's loadSelectedForecast method.
Implemented WeatherViewer's setPreferred method.
Implemented WeatherViewer's loadSavedCities method.
Implemented WeatherViewer's addSampleCities method.
Implemented WeatherViewer's addCity method.