allowing the none option on a simple select for assigned to on cardwall. Fix for request #3533

Change-Id: Idf16b7ee69c06380c987bab98972e6f85d31da34
Merge commit 'refs/changes/06/606/1' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  allowing the none option on a simple select for assigned to on cardwall. Fix for request #3533

Change-Id: Iec2ef628e39d60ccca6f73273c669106cb2e5a20
This is Tuleap 6.2.99.14

Change-Id: I1209a2547311b7b5a12de5860824a2d27f86034f