request #6725: have a more explicit button for project backlog

Change-Id: Id07eb70837172765ab872d0d80fc18a100ea5b61
Merge commit 'refs/changes/57/2357/2' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #6725: have a more explicit button for project backlog

Change-Id: Ie0aa66e89df103f5e104621c68594fb221ec5217
This is Tuleap 6.12.99.87

Change-Id: I88d1b4753b9fa8e5096f980cb2386b475558c32a