Add weather API section and add a forecast API

Created a `Weather API` section and added OpenWeatherMap API that provides forecast data and weather maps.

README.md

@@ -180,3 +180,8 @@ A collective list of JSON APIs for use in web development.
 | API | Description | OAuth |Link |
 |---|---|---|---|
 | Vehicle API | Lot of vehicles informations | No, but `apiKey` query string | [Go!](http://developer.edmunds.com/api-documentation/overview/) |
+
+### Weather
+| API | Description | OAuth |Link |
+|---|---|---|---|
+| OpenWeatherMap | Weather and Forecast API | No | [Go!](http://openweathermap.org/api) |