Contrast wider, header

Sets the header navigation off from the page in colour and layout:
* reenforces it as a separate type of action
* lightens the page by contrast
* letting it flow out of the page container makes it [easier to grab for touch users](http://www.lukew.com/ff/entry.asp?1721)

closes #572

![screen shot 2014-09-29 at 10 33 25 am](https://cloud.githubusercontent.com/assets/1239550/4436279/585eaa1a-4770-11e4-905a-d489b5124551.png)

![screen shot 2014-09-29 at 10 33 21 am](https://cloud.githubusercontent.com/assets/1239550/4436278/5859723e-4770-11e4-9c0b-9b075a0e1a14.png)