Add a meta viewport

Before:
![2014-12-05-19-12-23](https://cloud.githubusercontent.com/assets/930064/5320535/4b67173e-7cb3-11e4-94cc-1e48f59daf0f.png)

After:
![2014-12-05-19-01-47](https://cloud.githubusercontent.com/assets/930064/5320538/510c3656-7cb3-11e4-81d6-b8d40f181d28.png)

On firefox OS 2.1