Scala + S3

Everything new ! :smiley:

Refactored 90% of the frontend code. Introducing ActiveArray, a class managing the global state of the application. Every course add and delete callbacks are synchronized.

Now we are using a static JSON API hosted on Amazon S3. No more DB, no more Ruby, no more web servers, no more :poop: 

The Scala script used to generate the files is quite dirty and will be refactored soon.
A script to automatically deploy on S3 will be added later.