Support native captions in html5 tech.

Don't auto-add the textTrackDisplay component.
Add a 'featuresNativeTrack'. Currently hardcoded to false for everything
except the html5 tech.
Add textTracks and addTextTrack methods to html5 tech.
Proxy player level methods to tech if we're using native tracks.
Fix up track menu items to work with spec tracks or vjs tracks.

This is the beginning of step 1 for the [revamp](https://github.com/videojs/video.js/issues/1655) of text tracks.

* [x] Native tracks, if available
* [x] Re-use non-native otherwise
* [x] Chrome Support
* [x] Firefox support
* [x] iPad Support
* [x] Android support
  * [x] Chrome for Android -- works like desktop chrome
  * [x] Native Android Browser
* [x] IE Support
  * [x] IE11
  * [x] IE10
  * [x] IE9
  * [x] IE8 
* [x] Tests
This feels kinda dirty. Instead of relying on the video element being the first child of the player div, could we add a text track to TEST_VID and check that?

Also could we move this logic out of init and down around where canControlVolume is?
https://github.com/gkatsev/video.js/blob/ed27d85083d9a7ce74d958ad71aed0dc79d9c3f6/src/js/media/html5.js#L376