Add table header to rules table

Fixes #189 

Looks like:
![screen shot 2014-12-20 at 11 26 07 am](https://cloud.githubusercontent.com/assets/303711/5516026/8ea4f56e-883b-11e4-8f24-f07a991d226f.png)

And after rule deletion (and preventing page reload):
![screen shot 2014-12-20 at 11 26 32 am](https://cloud.githubusercontent.com/assets/303711/5516029/a6e7fe5a-883b-11e4-97a2-007318486bc5.png)