Git commits in Moodle 2.8.8 by Petr Skoda

commit 5337b2295237958c93b6c65fa595859aaa7bf257
Author: Petr Skoda <petr.skoda@totaralms.com>
Date:   Wed, 19 Aug 2015 05:33:12 +0800
Tag:    v2.8.8

MDL-50860 core: improve creation of random strings