Turn primary footer blue

Incorporates updated `guss-colours` and attendant updates to the header.

![screen shot 2014-08-07 at 17 07 38](https://cloud.githubusercontent.com/assets/867233/3844893/2814db32-1e4d-11e4-8b34-5c85b0da35b4.png)

is now

![screen shot 2014-08-07 at 17 08 00](https://cloud.githubusercontent.com/assets/867233/3844902/33cd64a8-1e4d-11e4-9b9a-fced3c1e1b3d.png)


![screen shot 2014-08-07 at 18 17 10](https://cloud.githubusercontent.com/assets/867233/3845818/ae79b7b6-1e56-11e4-8d78-180adcf19e8b.png) vs ![screen shot 2014-08-07 at 18 17 02](https://cloud.githubusercontent.com/assets/867233/3845820/b3055d44-1e56-11e4-8fa4-6a7759a9613e.png)

```html
<a href="/uk" data-link-name="site logo" class="guardian-logo-footer hide-on-mobile">
     <span class="u-h">The Guardian</span>
     <i class="i i-guardian-logo-160"></i>
</a>
```