Unittesting of javascript code: add infrastructure

[stefanoborini]

As we use more and more javascript side code, we would like to unittest it as well.
At the moment we only perform end-user testing with selenium, but nothing is done at the unittest level.

[stefanoborini]

https://qunitjs.com/

The problem is that it is aimed at the browser so we need to pass through selenium. If we factor out non-DOM manipulation, then we can probably use node.js to run them, and leave dom manipulation to the browser.

What about Rhino?

[itziakos]

It is something, that I have not done myself. In term of usability, I would like something that is easy to use and test on travis-ci.

[stefanoborini]

The PR adds just the infrastructure. Tests are missing (need to learn more about request and javascript) and will be added later.