Commercial: change class on collection with/without ads

Fixes

![screen shot 2014-04-15 at 11 35 13](https://cloud.githubusercontent.com/assets/74132/2706106/ae826a9a-c489-11e3-8596-f1c510d2035a.jpeg)

If a collection has an ad, it needs a different set of classes than without

TODO: simplify HTML when adding adverts to a collection