Git commits in Moodle 2.1.5 by Henning Bostelmann

commit 6a9b5984bdf479f85bacfb13c79554b79438286b
Author: Henning Bostelmann <henning.bostelmann@york.ac.uk>
Date:   Thu, 29 Dec 2011 01:47:22 +0800
Tag:    v2.1.5

MDL-30031 Adaptive question behaviour: ignore invalid answers without penalty