Use responsive design to make website useable on small screens (like phones)

![screen shot 2014-11-06 at 18 24 02](https://cloud.githubusercontent.com/assets/4432106/5151425/cd9e23a4-71ab-11e4-9dae-34e0a676462f.png)
![screen shot 2014-11-06 at 18 23 15](https://cloud.githubusercontent.com/assets/4432106/5151424/cd9e05cc-71ab-11e4-87b6-d96fe8524ef7.png)

Fixes #1691