Removes a element from constraints element

Fixes #272 

Overrides Blacklight `_constraints_element.html.erb` template

![screen shot 2014-06-30 at 11 32 56 am](https://cloud.githubusercontent.com/assets/1656824/3433974/fc3ecc42-0084-11e4-8f7f-7e786b4bd784.png)