tasks #6622 - Add field switch & display submit button

Change-Id: I92280a4433e78439dc8b8a5cb96a759adde9b86c
Merge commit 'refs/changes/56/2256/7' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  tasks #6622 - Add field switch & display submit button

Conflicts:
	plugins/tracker/include/trackerPlugin.class.php

Change-Id: I7d0aec3e5b8c4fdb9df708bb41d4be0eaf916264
This is Tuleap 6.12.99.30

Change-Id: Icbc33e42dbe05049eecdc4fa56d76c4cc6501a6e