Git commits in Moodle 3.0.0 by Pau Ferrer Ocaña

commit 60b69e4d2f590854ac3f720f1dbeed824f5b47e1
Author: Pau Ferrer Ocaña <crazyserver@gmail.com>
Date:   Wed, 23 Sep 2015 23:02:39 +0800
Tag:    v3.0.0-beta

MDL-50805 Messages: Add index to message_read to speed up message crons