Git commits in Moodle 2.7.20 by Andrew Nicols

commit 6cfcfff1189c3ce14eebf594d58ce9a0c2a85f5f
Author: Andrew Nicols <andrew@nicols.co.uk>
Date:   Wed, 03 May 2017 08:32:04 +0800
Tag:    v2.7.20

MDL-58746 core: Simplify environment check


commit 7a142305cffde08743de8f7c5a8ace420f735b58
Author: Andrew Nicols <andrew@nicols.co.uk>
Date:   Mon, 01 May 2017 08:51:37 +0800
Tag:    v2.7.20

MDL-58746 core: Add environment check for finfo