Design tweaks

* Added striped tables on all tables
* Added visibility hidden to blank rows
* Added classes to tables where null values are displayed, to drop the color back. This makes them not look as prominent.
* Added a background color to table headings.

Example preview:
![capture](https://f.cloud.github.com/assets/1252933/1099972/6960d172-1746-11e3-9ed5-b24e8d09cc4d.JPG)