Fixed issue with filters div that is bigger than containing div

The combination of the col-md-12 class and the margin-left styling on the div with the ng-controller attribute "FiltersCtrl" was causing the width of the div to over-extend the width of the page. You can see it by scrolling to the right on the page, a small gap will appear.

![gap](https://cloud.githubusercontent.com/assets/2916945/3608252/f8ed0fc0-0d5b-11e4-89c7-c644e0ce4b4c.jpg)

It's fixed by removing the col-md-12 class so that the filters class has a width of auto instead of 100% and adding padding-left: 15px and padding-right:15px to make up for the missing padding from that class.