Git commits in Moodle 3.1.4 by Davo Smith

commit 00b860d0d11078d91beb542e49684a36fa7cbc3b
Author: Davo Smith <git@davosmith.co.uk>
Date:   Thu, 16 Oct 2014 19:52:31 +0800
Tag:    v3.1.4

MDL-47198 filelib: fix curl handling headers with no value