[gh-443] Undefined property: stdClass::$roles in unl_cas_user_presave()

Sometimes a CAS user login error displayed when visiting a site for the first time:

User Anonymous (not verified) Location http://unlcms.unl.edu/erictest/user/cas?destination=node&ticket=ST-91014-YQCE6cjWUWZiAe4deJp7-cas Referrer Message Notice: Undefined property: stdClass::$roles in unl_cas_user_presave() (line 283 of /var/www/unl.edu/htdocs/sites/all/modules/unl/unl_cas/unl_cas.module).