Experiment in forward button impl

I'm not that happy with this version, but I'm going to branch it.
I think I should share a model with PlayerSubtitle containing
elapsed and stopwatch, that way the clocks are always in sync.
That also avoids the extra communication with an event.
Borrow a fun piece of CSS animation

This was my original idea, so I found some CSS3 based animation and
retro-fitted it.
Factor out boiler plate for CSS animations

use Sass mixins to remove repetitive boilerplate.
Take better advantage of Sass features
Change transform origin to be center, center
Add Request Animation Frame shim from Paul Irish
Switch to RequestAnimationFrame

instead of Janky setTimeout and setInterval switch over to
requestAnimationFrame and get 60fps on modern browsers.

- move all subtitle rendering into timer view.
- delete overly complex view using timeouts
- now pausing subtitle's actually pauses the subtitles.

Inspired by watching the famo.us guys talk about what they did to get
the best performance out of HTML:

http://youtu.be/f48_wJjmEw0