Fix Umbraco's error style propagating to elements in our view

Should fix the issue described in [this thread](http://our.umbraco.org/projects/backoffice-extensions/archetype/sound-off!/49058-Validation-seems-to-have-minor-issues?p=0), where valid properties are highlighted, due to one of Umbraco's styles propagating into our view when it recognizes the Umbraco property is invalid (after a Save)