Git merges in Moodle 2.2.4 by AMOS bot

commit adb1616724704b1a4af0189b4b4b93640adebd19
Author: AMOS bot <amos@moodle.org>
Date:   Tue, 26 Jun 2012 08:31:30 +0800
Tag:    v2.2.4

Merge branch 'MOODLE_22_STABLE' into install_22_STABLE