Ad tweaks

Tidying up some of the ad placement code and small styling bugs currently live

Examples of ads aligned with content:
![image](https://f.cloud.github.com/assets/1148714/2187424/00b23be4-97f6-11e3-9c43-581da7e0906e.png)
![image](https://f.cloud.github.com/assets/1148714/2187430/23cc0d4e-97f6-11e3-8296-409f9cb9886e.png)