Handle 'Out of page' adverts

Page skin adverts are created as 'out of page' adverts in DFP. For these to work we need to call a different GPT method

![1401389934_cute_kid_in_predator_costume](https://cloud.githubusercontent.com/assets/74132/3145964/30d3b046-ea3f-11e3-9886-c6809f7f63e3.gif)