Author: Ankit Agarwal
MDL-48559 cron: Disable web cron by default
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5254140b0c91c363d1e5f8b6aac217a5f7889bf6
http://github.com/moodle/moodle/commit/5254140b0c91c363d1e5f8b6aac217a5f7889bf6
+ 2.9 en [configcronclionly,core_admin]