Fix REST route /milestones/:id

Change-Id: I8936558e3e1117ab1c1ccfdc87b306c590fee11e
Merge commit 'refs/changes/17/1717/1' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  Fix REST route /milestones/:id

Change-Id: Ia4d5129eae6adb93fb81a3087820a7633b8f3929
This is Tuleap 6.9.99.22

Change-Id: I8d82034b4bb627a3e2e187d55326c473e114ad35