Git commits in Moodle 2.7.13 by Juan Leyva

commit 11106f6cee220119fcdcd101850741de7141399c
Author: Juan Leyva <juanleyvadelgado@gmail.com>
Date:   Wed, 27 Jan 2016 18:10:24 +0800
Tag:    v2.7.13

MDL-52901 mod_assign: Check due dates in external save_submission

commit c631b112d6e729c84f5d559371a399fe54502ba3
Author: Juan Leyva <juanleyvadelgado@gmail.com>
Date:   Mon, 18 Jan 2016 22:06:36 +0800
Tag:    v2.7.13

MDL-52808 calendar: Do not return events for hidden activities