Author: Dan Marsden
MDL-60347 core: debugsmtp should be a developer only setting.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8c678d9aa9b862cabb7339f07d3a933955aa0cd4
http://github.com/moodle/moodle/commit/8c678d9aa9b862cabb7339f07d3a933955aa0cd4
+ 3.5 en [configdebugsmtp,core_admin]