Story #7509 - add expand/collapse bar containing backlog item's children

Change-Id: I7768d1c95e17d06e148e17bfc3fc47c2b56215d5
Merge commit 'refs/changes/96/3196/8' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  Story #7509 - add expand/collapse bar containing backlog item's children

Change-Id: I49030b0545003bc594f3bba1dbbe55c753d35a3c
This is Tuleap 7.6.99.45

Change-Id: I28ebaea90a91b92212550f2dd1ddde415197ce4e