Author: Paul Holden
MDL-75805 admin: allow multiselect when editing site administrators.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=253c0412970a4d5356216c40cebda7c9d8593c2a
http://github.com/moodle/moodle/commit/253c0412970a4d5356216c40cebda7c9d8593c2a
+ 4.2 en [confirmaddadmins,core_role]
+ 4.2 en [confirmremoveadmins,core_role]