Author: Zig Tan
MDL-61881 report_usersessions: Implement null privacy provider
http://git.moodle.org/gw?p=moodle.git;a=commit;h=192e9b2e1e59e93bf771a9af7106bd0b144fc07c
http://github.com/moodle/moodle/commit/192e9b2e1e59e93bf771a9af7106bd0b144fc07c
+ 3.3 en [privacy:metadata,report_usersessions]