Reducing z-index on android ad items

Before;
![screen shot 2014-12-04 at 10 06 25](https://cloud.githubusercontent.com/assets/1303616/5296560/4b9cd336-7b9d-11e4-8fac-ea5adac52948.png)

After;
![screen shot 2014-12-04 at 10 06 47](https://cloud.githubusercontent.com/assets/1303616/5296562/51332eb2-7b9d-11e4-9b90-7ebf1bf512c3.png)