Development: return the number of artifacts in rest lib

Change-Id: Ifcd5692ce51156b35e363f636bbe4f96df848c43
Merge commit 'refs/changes/82/2882/1' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  Development: return the number of artifacts in rest lib
This is Tuleap 7.3.99.50

Change-Id: I23af5e555a4dbe05f3a4b70d1558f600619088bd