Decouple Aeolus from OWM service. Allow easy switch of services.

Aeolus shouldn't be coupled to one weather service. It should be possible to easily switch between services. A switch should require minimum amount of code changes.

To do so, Aeolus should maintain in its memory the exact weather data required by the services. All Aeolus operations should be based on (use) those data. Only the parser functions and the service contact functions should change. There should be separate parser functions and service contact functions for each service (OWM, Yahoo, etc).