Converted XModule to JavaScript. Added Jasmine tests.

Part of the process for removing CoffeeScript from
edx-platform dependencies. Covering XModule with JavaScript
Jasmine unit tests.
Merge pull request #3126 from edx/valera/convert_xmodule_to_javascript

Converting XModule module to JS.
HD control is disabled initially. It eventually gets enabled on first play of video, when player.getAvailableQualityLevels returns on non-empty array. [BLD-937]
Addressed comments.
Hide HD button on initialization instead of disabling. Show it if HD available instead of enabling.