Implements PUT /artifacts/:id

+ update OPTIONS and add tests

Change-Id: I27585d4dbbb339962ed732226f11e318c13722a3
Implements OpenList and PermissionsOnArtifact fields for REST

Change-Id: I515b0757a19c09b8ab35953503feb98d2623f392
Implements POST /artifacts

Change-Id: I3c220de482fda10df5ff4f49359cace5f9f7df52
Add OPTIONS on /artifacts

+ Better coverage of tests on changesets and comments

Change-Id: I353e17b4b33f08f9622eaf51f1ec716bcfed549c
Merge remote-tracking branch 'gerrit/6191_rest_put_post_artifacts' into tuleap-stable-master

* gerrit/6191_rest_put_post_artifacts:
  Add OPTIONS on /artifacts
  Implements POST /artifacts
  Implements OpenList and PermissionsOnArtifact fields for REST
  Implements PUT /artifacts/:id

Change-Id: I3badd70ea4af50f17b15f6e7905340abd7eb65ec
Tuleap 6.10.99.52

Change-Id: I5f37ef0bf4ec3de42eb7c7995087a8fd5e9f745f