Author: Iñaki Arenaza
MDL-16168 auth/cas CAS crashes if no LDAP is set up
Fix was pending for Moodle 2.1. Credit goes to Ivan Dackiewicz.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b38bcc3a1d5634ce81b823e0b078db3a81759fe8
http://github.com/moodle/moodle/commit/b38bcc3a1d5634ce81b823e0b078db3a81759fe8
+ 2.1 en [noldapserver,auth_cas]