Create 'track' element in the HTML5 shiv sample

Matches the shiv to the one at [the start of `src/js/core.js`](https://github.com/videojs/video.js/blob/master/src/js/core.js#L8).

Right now it's missing `track`.
Merge pull request #1005 from uniphil/patch-1

Create 'track' element in the HTML5 shiv sample