Git commits in Moodle 2.7.8 by Dan Bennett

commit 5b1e0822ac997f450cb6a7d5e693ca483b1aedcc
Author: Dan Bennett <dan@howtomoodle.com>
Date:   Tue, 10 Mar 2015 00:13:52 +0800
Tag:    v2.7.8

MDL-49104 repository_s3: backport of MDL-43725