See grand-children of an artifact in its hierarchical view

Change-Id: Ie4dee9ea6e366f01de38dfc6bb13d1efe72117f5
Merge commit 'refs/changes/50/350/3' of http://gerrit.tuleap.net/tuleap into stable

* http://gerrit.tuleap.net/tuleap:
  See grand-children of an artifact in its hierarchical view
This is Tuleap 5.12.99.14