Invert option to filterbar filters

Closes #2344 

- Adds invert toggle to filters
- Changes text to icons ![screenshot 2014-12-17 14 38 21](https://cloud.githubusercontent.com/assets/404731/5479432/7ace6284-85fa-11e4-8ba6-27382b79b946.png)

![2014-12-17 14_43_02](https://cloud.githubusercontent.com/assets/404731/5479498/0b44835c-85fb-11e4-9320-18d429cc81eb.gif)

![bang bang](https://s3.amazonaws.com/uploads.hipchat.com/29251/211439/0KHAHOr1L1myDca/200-2.gif)