Author: Jackson D'souza
MDL-69088 cache: Make file cache store purge async
http://git.moodle.org/gw?p=moodle.git;a=commit;h=18de3388f8b66493485402dee17ad04e4eeecf6c
http://github.com/moodle/moodle/commit/18de3388f8b66493485402dee17ad04e4eeecf6c
+ 4.0 en [asyncpurge,cachestore_file]
+ 4.0 en [asyncpurge_help,cachestore_file]
+ 4.0 en [task_asyncpurge,cachestore_file]