Removes the link from constraints text

Fixes #938 

This PR rewrites the `_constraints_element.html.erb` partial and removes the anchor element from the constraint text. This is what we are implementing in SearchWorks https://github.com/sul-dlss/SearchWorks/pull/376

![screen shot 2014-06-30 at 11 32 56 am](https://cloud.githubusercontent.com/assets/1656824/3435654/dad60eea-0097-11e4-92b6-bed530b45ed7.png)