Author: Neill Magill
MDL-65443 core: Log when a context is locked or unlocked
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e8b4c32290e26fd4a8e36dc29496fe597f02a155
http://github.com/moodle/moodle/commit/e8b4c32290e26fd4a8e36dc29496fe597f02a155
+ 3.6 en [eventcontextlocked,core_access]
+ 3.6 en [eventcontextunlocked,core_access]