Fancybox (single image and image gallery)

![image](https://cloud.githubusercontent.com/assets/1814983/3527435/0112db44-0785-11e4-9525-3faceb91d2bc.png)

![image](https://cloud.githubusercontent.com/assets/1814983/3527443/12475584-0785-11e4-805b-e0ef7e7b6496.png)

Prefer `before_action` over `before_filter`.