Media player rewrite

This rewrites both the video and audio players to use a new UI and a unified codebase. It also makes the code less horrible and gives us a dedicated place to put more playback options (like subtitles).

Current UI (for comparison):

![2014-01-12_00 27 18](https://f.cloud.github.com/assets/1310872/1895811/6d4e5ee0-7b63-11e3-961f-b47ede5c9df4.png)

New UI:

![2014-01-12_00 11 30](https://f.cloud.github.com/assets/1310872/1895814/76ba1140-7b63-11e3-87df-42a9cb6f3f7a.png)
![2014-01-12_00 11 48](https://f.cloud.github.com/assets/1310872/1895815/76d766fa-7b63-11e3-99c5-abb7b99f1ab4.png)
![2014-01-12_00 11 59](https://f.cloud.github.com/assets/1310872/1895816/76d78824-7b63-11e3-8c88-51abd328ec4c.png)