Fix namespace error on /artifacts/:id routes

Change-Id: Ie34dbde3b56cc59ae251be7193caa4338b613041
Merge commit 'refs/changes/14/1514/1' of http://gerrit.tuleap.net/tuleap into tuleap-stable-master

* http://gerrit.tuleap.net/tuleap:
  Fix namespace error on /artifacts/:id routes

Change-Id: Ic2e806818d17e320d247bfbd14c0650246a7eb62
Tuleap 6.7.99.16

Change-Id: Id2d3365df891f85970315e9d003932efdf438bf1