Merge pull request #52 from NicolasKessler/master

Implemented the database and the asynch loading of the data, aswell as saving the favorites to the database. TODO: decision from where to load
(web or database) + better error management in model creation + proper oberserver pattern between GUI and Model
Merge pull request #53 from NicolasKessler/master

better error management for downloading and some small enhancements