Git commits in Moodle 3.6.4 by sam marshall

commit 2327fedbea4c6a0c99f417e1476afe6fb0970812
Author: sam marshall <s.marshall@open.ac.uk>
Date:   Thu, 18 Apr 2019 22:04:15 +0800
Tag:    v3.6.4

MDL-65375 Restore: Null data in other field should be serialised

commit 00c706dc8a57a0500aa90bfd107ace347eeb617d
Author: sam marshall <s.marshall@open.ac.uk>
Date:   Fri, 01 Mar 2019 01:36:30 +0800
Tag:    v3.6.4

MDL-64979 Behat: Add option to increase timeouts