Author: Michael Hawkins
MDL-83352 message: Update usercantbemessaged string
http://git.moodle.org/gw?p=moodle.git;a=commit;h=92a2dcc96af1a421807549fb5e71d5c39e2addc5
http://github.com/moodle/moodle/commit/92a2dcc96af1a421807549fb5e71d5c39e2addc5
+ 4.1 en [usercantbemessaged,core_message]