Slap in 30 day CSS/JS filesize analysis

- Adds 30 day stat to CSS and JS indexes
- Graph now only shows last 7 days

![screen shot 2014-08-06 at 14 14 18](https://cloud.githubusercontent.com/assets/271645/3827236/9ec3be48-1d6b-11e4-8c5a-ab59518bd445.png)