Git merges in Moodle 3.1.8 by Eloy Lafuente (stronk7)

commit 93cca9afbe2671ae7153fb9bee7febdda0351a71
Author: Eloy Lafuente (stronk7) <stronk7@moodle.org>
Date:   Sun, 10 Sep 2017 04:47:57 +0800
Tag:    v3.1.8

Merge branch 'install_31_STABLE' of https://git.in.moodle.com/amosbot/moodle-install into MOODLE_31_STABLE

commit f883e3172815f37035c79730a897b488107a41ae
Author: Eloy Lafuente (stronk7) <stronk7@moodle.org>
Date:   Tue, 11 Jul 2017 16:18:31 +0800
Tag:    v3.1.8

Merge branch 'MDL-57432-31' of git://github.com/danpoltawski/moodle into MOODLE_31_STABLE