Git merges in Moodle 1.9.18 by Dan Poltawski

commit a9375cc95d5bc70a49d782bd8c070be33bd42d5a
Author: Dan Poltawski <dan@moodle.com>
Date:   Mon, 07 May 2012 15:32:53 +0800
Tag:    v1.9.18

Merge branch 'MDL-18335b_m19' of git://github.com/rwijaya/moodle into MOODLE_19_STABLE