add support for JavaScript Tutor

[pdawyndt]

The JavaScript Tutor is a sister of the Python Tutor that can be integrated in Dodona, such that users can launch it directly for a given context.

Original issue by @pdawyndt on Thu Apr 27 2017 at 07:23.

[pdawyndt]

@dmouriss can you see if your experience with setting up the Python Tutor would make it easy to have a similar setup for the JavaScript Tutor. Probably we will not need the option to work with local files in JavaScript, at least not in the near future.

Original comment by @pdawyndt on Thu Apr 27 2017 at 22:33.

[dmouriss]

This might lead to needing a special renderer for the javascript exercises. But I will have a look at it.

Original comment by @dmouriss on Fri Apr 28 2017 at 10:22.