Author: Sam Hemelryk
MDL-37470 cache: definitions can now be purged through config screen
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5052356574813655713ae123204b57a3b45000f4
http://github.com/moodle/moodle/commit/5052356574813655713ae123204b57a3b45000f4
+ 2.5 en [purgedefinitionsuccess,core_cache]