KnoxSSO Redirect Back to External App has CORS Problem for Form IDP

Issue identified with external application integration for form based login page. When the redirect is attempted from XmlHttpRequest result, the fact that an application like Ambari is not from the same origin causes the browser to not allow the redirect back.

CORS support in the external application would fix this but is also a burden that we should try and avoid.

Need to investigate the best way around this - if any.