Fix bugs #3582 - getTrackerStructure permissions

SOAP method getTrackerStructure returns fields visible by user
instead of requiring admin permission.

Change-Id: Iafdb79916d4c4076146a33392d1a169e25081b7c
Merge commit 'refs/changes/48/448/1' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix bugs #3582 - getTrackerStructure permissions

Change-Id: I4ac253774b64b7a69890b8284f97fb0a27a1ae40
Tuleap 6.1.99.2

Change-Id: I206e6547cef699658b972200e569f4f23d2c8d14