Author: Mihail Geshoski
MDL-64745 block_online_users: Option to disable users to set visibility
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e1fb8e4aec22ac1dd9ff5d8154a6b64396d237cb
http://github.com/moodle/moodle/commit/e1fb8e4aec22ac1dd9ff5d8154a6b64396d237cb
+ 3.8 en [onlinestatushiding_desc,block_online_users]
+ 3.8 en [onlinestatushiding,block_online_users]