Display the archived artifacts URL on the project detail view

Fixes #83
As I've explained, we allow users to edit the archiving task out of the settings.py, this implies strongly that not-archiving items is not an error condition, and _might_ be desirable.

IMO, we should use the table-striping, but have a title on each <tr> element indicating whether or not it was archived, or if it's still in Jenkins.