Changed "Download Firefox" to Standard Download Button

Before and after the changes.
![screenshot from 2014-06-07 13 18 03](https://cloud.githubusercontent.com/assets/1151263/3208072/88bab778-ee18-11e3-8ea4-c20e9e46239d.png)
![screenshot from 2014-06-07 13 18 17](https://cloud.githubusercontent.com/assets/1151263/3208075/9fc8d9ea-ee18-11e3-90c3-8f5c56efe8f8.png)