Update Video.JS to 4.8.1

In this pull request i will update the plugin to Video.JS version 4.8.1. It won't be backward compatible.

I updated Video.JS already in the *demo/* directory, so it can be tested.

**Fixes:**
* Update features API
* Stop player didn't switched back to the HTML5 player
* Do not hide the controls on the ChromecastTech
* Localization (new feature)