Git commits in Moodle 3.1.2 by Michael Aherne

commit e2c0f3ee50623fcb827b86ba422d158002a88b69
Author: Michael Aherne <michael.aherne@strath.ac.uk>
Date:   Fri, 08 Jul 2016 17:48:00 +0800
Tag:    v3.1.2

MDL-55161 assign: Check for existence of gradebook feedback plugin