Ad banner top desktop

- [new] ads slots can be out of the context (`#preload-1`)
- [new] if LeadAdTopPageSwitch is on, the lead ad is placed on top of the page on desktop

This will not be switched on in production. Design tweaks will be implemented, with CODE as a test environment.

![screen shot 2014-03-11 at 14 53 47](https://f.cloud.github.com/assets/85783/2386532/2c0ca944-a92d-11e3-9019-512f0d6da4d9.PNG)

![ ](http://media2.giphy.com/media/6imitJQNkU78k/giphy.gif)