Git commits in Moodle 2.8.x by Marc Català

commit f81f6bbda5e50e4c959ed99f7e9e4306e20c8e30
Author: Marc Català <reskit@gmail.com>
Date:   Sat, 20 Jun 2015 19:02:22 +0800
Tag:    v2.8.7

MDL-50652 workshop: Workshop module allows duplicated ID number