Author: Paul Damiani
MDL-63569 email: New setting to prefix the subject of outgoing emails
http://git.moodle.org/gw?p=moodle.git;a=commit;h=9ffbb786686a046730a8c7047f14ef63f5e450bf
http://github.com/moodle/moodle/commit/9ffbb786686a046730a8c7047f14ef63f5e450bf
+ 3.7 en [configemailsubjectprefix,core_admin]
+ 3.7 en [emailsubjectprefix,core_admin]