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=e3ec42093ad67884f25abe5cb79155eeda53655e
http://github.com/moodle/moodle/commit/e3ec42093ad67884f25abe5cb79155eeda53655e
+ 3.8 en [eventcontextlocked,core_access]
+ 3.8 en [eventcontextunlocked,core_access]