Git commits in Moodle 3.1.x by JD

commit 9b81a977e13d613c61634c0d580129e48b10bccc
Author: JD <jdescoteaux@hotmail.com>
Date:   Wed, 13 Jul 2016 07:45:08 +0800
Tag:    v3.1.2

MDL-54977 blocks_navigation: Use html_writer::random_id for id