Merge remote-tracking branch 'bender/master' into 5912_put_milestones_id_milestones

* bender/master:
  This is Tuleap 6.9.99.22
  Fix REST route /milestones/:id

Change-Id: I7b581d6fd615c93646b00b487e008101bf7c58bb
Implementing PUT on milestones/:id/milestones

Change-Id: I6a1e9a9c79dcb474042298f565f65bf84c1e0dad
Tests for PUT milestones/:id/milestones

Change-Id: Ie19757ec682ceb2fae1d5cdf75adabe897940817
Rest exceptions have more meaningful error codes (4xx -> 5xx)

Change-Id: I0570a229bb7b821649574f6fa17dd1a10d51f7a6
Merge remote-tracking branch 'gerrit/5912_put_milestones_id_milestones' into tuleap-stable-master

* gerrit/5912_put_milestones_id_milestones:
  Rest exceptions have more meaningful error codes (4xx -> 5xx)
  Tests for PUT milestones/:id/milestones
  Implementing PUT on milestones/:id/milestones

Change-Id: If0c0b22b5b71a49859c4bb34a1c09c78630a7f7d
Tuleap 6.9.99.23

Change-Id: I5d447f2b4f560887b635af61a37bd7bc51fb5e52