Author: Andrew Davis
MDL-31429 enrol: added db/messages.php for enrolment plugins and added some smarts to messaging so it won't display message settings for disabled enrolment plugins
http://git.moodle.org/gw?p=moodle.git;a=commit;h=1218879656fa4b5d89e8a661e5f5f339a6da4c56
http://github.com/moodle/moodle/commit/1218879656fa4b5d89e8a661e5f5f339a6da4c56
+ 2.3 en [messageprovider:flatfile_enrolment,enrol_flatfile]
+ 2.3 en [messageprovider:imsenterprise_enrolment,enrol_imsenterprise]