request #6117: add pagination headers for rest routes

 * GET milestones/:id/content
 * GET milestones/:id/backlog

Change-Id: Ic2a60b5c65fe62f8ec4a46f15fcb7f37f51e33a2
request #6104 : PUT with no change returns 200

Change-Id: I79b58ab8e19d2327afde6b51493bad135cf41e4f
Merge commit 'refs/changes/00/2000/1' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #6104 : PUT with no change returns 200
  request #6117: add pagination headers for rest routes

Change-Id: I13ffb3bb3530994fbd08991bc5fadc6efbe2936d
Tuleap 6.10.99.51

Change-Id: I7c8b89be15a931210933f9089dcbef31c0c060ed