add "paused" symbol with CSS

First of all: Excellent work, components should have existed long before!
I've added "pause" and "play" symbols to corresponding states.
Used two `25AE` for pause button. looks like this:
![Playing Audio](https://f.cloud.github.com/assets/498704/46643/8da497ce-5880-11e2-8e43-9c6f04c4630d.png)