Git commits in Moodle 2.5.5 by James Pratt

commit 7cd9c85868bd9e6b5eef15c364d424286511e59e
Author: James Pratt <me@jamiep.org>
Date:   Fri, 13 Dec 2013 18:15:41 +0800
Tag:    v2.5.5

MDL-43369 : quiz statistics - average across attempts