style atl table rows grey / white / grey etc

I added alternating colours to table rows for better readability. See before and after screenshots below:


![screen shot 2014-05-13 at 10 05 31 am](https://cloud.githubusercontent.com/assets/145042/2952015/6a045acc-da32-11e3-9c97-ba14a50345b1.png)
![screen shot 2014-05-13 at 10 04 21 am](https://cloud.githubusercontent.com/assets/145042/2952019/6c2f3772-da32-11e3-9762-09c163245182.png)


Signed-off-by: Joshua Paling <joshua.paling@gmail.com>