Tahi-project/tahi — pull request #715 by egh (2014-12-11 23:09:44+00:00)
Title: allow configuration of CAS via envvar

configure CAS via env vars, useful for heroku and other 12-factor app servers

e.g. set:
```
CAS_HOST=...
CAS_LOGIN_URL=/cas/login
CAS_PORT=443
CAS_SERVICE_VALIDATE_URL=/cas/serviceValidate
CAS_SSL=true
```