Author: Charles Fulton
MDL-45113 auth: add is_configured method and convert auth_db to use it
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b6f28375b7572fe791f391e91f47fe3fd402fc7f
http://github.com/moodle/moodle/commit/b6f28375b7572fe791f391e91f47fe3fd402fc7f
+ 3.0 en [auth_notconfigured,core_auth]