passport: fix CAS authentication when no sub path
passport: fix CAS authentication when no sub path

Authentication using CAS wasn't working when CAS
URL didn't contain sub path (e.g.
https://my-cas-server instead of
https://my-cas-server/cas).
This issue appeared in current version (not
released yet).

veo-labs/openveo-api,veo-labs/openveo-api