Issue7

When there is a ticket validation exception, we return to the IDP a StatusCode.NO_PASSIVE_URI or StatusCode.AUTHN_FAILED_URI (passive if we tried gateway=true). 

Please note - I verified in the logs that the correct code is being sent back, but if you use the https://sp.testshib.org page, the site simply reports AuthnFailed. ie:

```
11:42:02.993 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:497] - Authenticating user with login handler of type net.unicon.idp.authn.provider.CasLoginHandler
11:42:10.100 - ERROR [net.unicon.idp.externalauth.CasCallbackServlet:70] - Unable to validate login attempt.
org.jasig.cas.client.validation.TicketValidationException: 
		'service' and 'ticket' parameters are both required
...
...
11:42:10.100 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:144] - Returning control to authentication engine
11:42:10.101 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:209] - Processing incoming request
11:42:10.101 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:514] - Completing user authentication process
11:42:10.101 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:585] - Validating authentication was performed successfully
11:42:10.101 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:595] - Error returned from login handler for authentication method urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified:
**urn:oasis:names:tc:SAML:2.0:status:NoPassive**
11:42:10.102 - DEBUG [edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine:161] - Returning control to profile handler
```