Replace TinyMCE by CKEditor in docman

This is a first step to remove TinyMCE from Tuleap.

See request #6589

Change-Id: I81e917f2d6e7e93746a24178f623cd60df1e8ea8
Merge commit 'refs/changes/17/2217/2' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  Replace TinyMCE by CKEditor in docman

Change-Id: I19ba9d4068c3fd38693a3f505c33803202408cda
Tuleap 6.11.99.47

Change-Id: I7573a57bdd5f4c9c9bda5432a4586c24ccc99574