Add the Javascript course

We'll have our first Javascript class soon, so we'll need the course option in Bridge Troll! :ocean: 

For the trial run, we're targeting people who have no experience with javascript. So I'm only including two levels, one for previous programming experience in a language like ActionScript, Java or Ruby, and one for familiarity with only HTML and CSS. I would love suggestions for those descriptions! 

We should definitely build these levels out after this trial run. :racehorse: