Git commits in Moodle 3.1.5 by David Mudrák

commit fe785db8db37f240def9560683379bbf66a1678c
Author: David Mudrák <david@moodle.com>
Date:   Tue, 07 Mar 2017 19:56:28 +0800
Tag:    v3.1.5

MDL-58064 lang: Clarify the PHP 7.x limitations

commit 3fe3805d79afd682358aa31a6014792efe1c4313
Author: David Mudrák <david@moodle.com>
Date:   Tue, 14 Feb 2017 05:49:33 +0800
Tag:    v3.1.5

MDL-57597 competency: Fix serving of prior learning evidence files

commit e611797d3769e2cb1607f8f9390ba61853d59cc0
Author: David Mudrák <david@moodle.com>
Date:   Wed, 18 Jan 2017 02:27:57 +0800
Tag:    v3.1.5

MDL-57677 mod_forum: Fix wrong user displayed as the last post's author