Author: Zig Tan
MDL-61881 report_usersessions: Implement null privacy provider
http://git.moodle.org/gw?p=moodle.git;a=commit;h=71098b95247b5c35c4d1dc1b4c6beb5312a3de90
http://github.com/moodle/moodle/commit/71098b95247b5c35c4d1dc1b4c6beb5312a3de90
+ 3.5 en [privacy:metadata,report_usersessions]