Fix display of need IDs in artefacts table

Bootstrap 3 requires a `label-default` class

Before:
![screen shot 2014-08-29 at 15 01 38](https://cloud.githubusercontent.com/assets/319055/4091116/0be6a690-2f85-11e4-925d-2b4eb0dfa0f3.png)

After:
![screen shot 2014-08-29 at 15 01 46](https://cloud.githubusercontent.com/assets/319055/4091117/0bebbfae-2f85-11e4-8194-861fe37eaac4.png)