Author: Iñaki Arenaza
MDL-16168 auth/cas CAS crashes if no LDAP is set up
Fix was pending for master. Credit goes to Ivan Dackiewicz.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=ab8b1d15a514d1a47c579406491962e53bc15789
http://github.com/moodle/moodle/commit/ab8b1d15a514d1a47c579406491962e53bc15789
+ 2.2 en [noldapserver,auth_cas]