Use MongoDB for data storage instead of static json files.

This means you need to feed the data into your MongoDB database ('worldcup2014') for the app to work. There is (commented out) routing in index.js to cache that can import the static json files into MongoDB:
- uncomment the routing
- load /api/cache/import
- load /api/data (to load from DB and check everything is fine)
Release version v0.3.0