Author: Arnaud Trouve
MDL-53044 auth : force change on expired password
http://git.moodle.org/gw?p=moodle.git;a=commit;h=ca8ccd3960c6bcb94344047088d55f51010ca6e2
http://github.com/moodle/moodle/commit/ca8ccd3960c6bcb94344047088d55f51010ca6e2
+ 3.1 en [auth_passwordisexpired,core_auth]