Git merges in Moodle 2.7.15 by Andrew Nicols

commit 719293b5b06a3ef0b24e2469f5a5ced209503deb
Author: Andrew Nicols <andrew@nicols.co.uk>
Date:   Mon, 04 Jul 2016 09:15:13 +0800
Tag:    v2.7.15

Merge branch 'MDL-53019_27' of git://github.com/stronk7/moodle into MOODLE_27_STABLE