Use flask blueprint

Final step in the blueprints effort (see #35)

This time more stuff will change.

- No routes on the central app object. One idea with Blueprints is to decouple the specific app object from the routes. I've added a new Blueprint, represented by the "browser" subpackage. Blueprints (and thereby routes) are registered in the "create_app" function (the app factory).

- A moves all views/routes to the "views.py" module in the browser subpackage.

- I've continued to move all necessary settings into the Flask app config object so that they can be set in any Flask compatible way.

Let me know if you need more specific explanations.