Git merges in Moodle 2.5.8 by AMOS bot

commit a0f183ae84e1f9cf2b9351b03bc53d395176f9e8
Author: AMOS bot <amos@moodle.org>
Date:   Sat, 06 Sep 2014 00:05:49 +0800
Tag:    v2.5.8

Merge branch 'MOODLE_25_STABLE' into install_25_STABLE