Fixed paths to deploy and restructured files

* Placed the video player styles into video-player.css to be more clear
about what is default and what is for the demo.
* Placed demo styles into styles.css
* Changed <article> and <aside> to <div>s with their new classes.
* Fixed the path in scripts. Moved the script to video-player.js so
that it is more clear what is part of the player and what is part of
the demo.