Commercial Fluid 250 template changes

This adds the option to remove the "Advertisement" label from the ad for in-house promotions.

Also up the z-index of the "from the guardian" menu on mobile so it always sits above the advert.

Before;
![screen shot 2014-12-04 at 14 00 03](https://cloud.githubusercontent.com/assets/1303616/5299328/0ca2bab2-7bbe-11e4-8cb5-e508c3d158f7.png)

After;
![screen shot 2014-12-04 at 14 00 33](https://cloud.githubusercontent.com/assets/1303616/5299331/12b993f8-7bbe-11e4-87f3-1b508e4b3131.png)

hide is a modifier of the label element, so class should be something like `creative__label--hidden`