Add GET and OPTIONS route for project/:id/milestones

Change-Id: I6374f34cca9222cb0ea1f7c49dd9b32b2969dbeb
Factoring REST pagination headers

Change-Id: If7da10041bcf5808c614bd58f351b25183e2328d
Merge remote-tracking branch 'gerrit/5580_project_milestones' into HEAD

* gerrit/5580_project_milestones:
  Factoring REST pagination headers
  Add GET and OPTIONS route for project/:id/milestones

Change-Id: Ib1a181658e3be5aeab0f9035fc8bc6308cc74ab2
This is Tuleap 6.7.99.11

Change-Id: Id935b187b721dc360ee7f0426bb8b5ad3e759ded