Updated reader view for mobile devices.

@jone I've improved the **mobile** view of the ftw.book reader view. The desktop view doesn't change

##before
![bildschirmfoto 2014-03-12 um 08 30 46](https://f.cloud.github.com/assets/157533/2394643/64b71e1a-a9b8-11e3-81d7-03384a7825cb.png)

##after
![bildschirmfoto 2014-03-12 um 08 28 13](https://f.cloud.github.com/assets/157533/2394642/64b6d572-a9b8-11e3-93d8-819ab42c0288.png)