Git commits in Moodle 2.4.x by Mike Churchward

commit d75a987e36e68f9c3000fb93e85ea42dd5fa38a2
Author: Mike Churchward <mike@remote-learner.net>
Date:   Wed, 17 Apr 2013 22:31:46 +0800
Tag:    v2.4.4

MDL-34933 core_message: Adding index to improve database access on message_working table.