Add weather notification (#846)

This pull request is to fix https://github.com/DroidPlanner/droidplanner/issues/846.

Right now I have:
- draft weather object model is implemented (e.g. you can get Wind speed and bearing)

Now I need:
-  some guiding on implementing it in GUI

Usage example:


    WeatherDataProvider weather = WeatherDataProviderFactory.getInstance(ProviderType.OPEN_WEATHER_MAP, new AsyncListener() {
    				
    				@Override
    				public void onResult(WeatherItem item) {
    					Wind wind = (Wind) item;
    					Log.d("Wind speed", "Speed: " + wind.getSpeed());
    					
    				}
    				
    				@Override
    				public void onError(String reason) {
    					Log.e("Wind error", reason);
    					
    				}
    			});
    			
    			weather.getWind(new Coord2D(0,0));