Git commits in Moodle 3.3.1 by Alexander Bias

commit 2a615a6031dc4a9eb05cee0e1ffb07c9794a4ca2
Author: Alexander Bias <alexander.bias@uni-ulm.de>
Date:   Wed, 17 May 2017 14:20:09 +0800
Tag:    v3.3.1

MDL-58165 navigation: Add node key to private files navigation node