Checked site wrapper class exists on all pages, and spans entire page

Fixed problems where images don't fill the full width of the iPad screen (tested on iPad simulator).

Also works fine in landscape on iPad.
'Paying-through-gocardless' is a responsive page, so no need for it on that page.

**Note:** Nav bar and text on some pages could benefit from more gutter/padding at the sides of the screen.

ie. moved from this:
![screen shot 2014-10-09 at 12 25 27](https://cloud.githubusercontent.com/assets/2903904/4575420/15a79508-4fa7-11e4-9515-6ae0bcba8036.png)
![screen shot 2014-10-09 at 12 25 33](https://cloud.githubusercontent.com/assets/2903904/4575422/17070c4e-4fa7-11e4-910e-98af50164c6a.png)

To this:
![screen shot 2014-10-09 at 12 26 54](https://cloud.githubusercontent.com/assets/2903904/4575433/32e83884-4fa7-11e4-86bd-23318c576c68.png)
![screen shot 2014-10-09 at 12 26 58](https://cloud.githubusercontent.com/assets/2903904/4575434/377b927e-4fa7-11e4-9b05-c8976597a839.png)