Only linkify full urls in validation results (bug 726057)

Fixes [bug 726057](https://bugzilla.mozilla.org/show_bug.cgi?id=726057)

![validation](https://cloud.githubusercontent.com/assets/167767/4629605/01ddbc0c-53a6-11e4-8a54-c3d2180db40a.png)
`the²`