Git commits in Moodle 3.0.8 by David Mudrák

commit 00e928271b1f07426a635551c32d9d9502e7e336
Author: David Mudrák <david@moodle.com>
Date:   Thu, 05 Jan 2017 20:20:59 +0800
Tag:    v3.0.8

MDL-57580 mod_assign: Fix the incorrect type of some input parameters


commit ae375cfcdcd3e16f273954463770ca452d056af9
Author: David Mudrák <david@moodle.com>
Date:   Wed, 04 Jan 2017 20:05:03 +0800
Tag:    v3.0.8

MDL-57531 mail: Validate the sender's email address


commit 1c25f894ef7544e59ec51986bd650359277a66b1
Author: David Mudrák <david@moodle.com>
Date:   Wed, 04 Jan 2017 19:30:18 +0800
Tag:    v3.0.8

MDL-57531 mail: Do not let admins set invalid email addresses


commit ef7442df5b853fc82f38fa82c853efe26fd0dba1
Author: David Mudrák <david@moodle.com>
Date:   Wed, 04 Jan 2017 17:58:44 +0800
Tag:    v3.0.8

MDL-56225 mod_forum: Fix inability to edit attachments