minimized embeddable.js, simplified application.js

The interactive controller is now responsible for
loading the Interactive JSON.

application.js is now only used in interactives.html

In addition the code that worked directly with the webapp has been removed.

embeddable.html now uses embeddable.js (now only 41 lines of code).

TODO: more simplification and refactoring of application.js
so it is easier to create alternate versions which
use components like JSON code editors etc.