Support for new CAS OAuth Server Implementation

To run this demo do a `mvn install` on joemccall86/cas@master to get the custom 4.0.0-SNAPSHOT in your local maven repository.

This is still a work in progress, but what I have in this pull request shows a working demo of the new oauth support. As you can see in cas-servlet.xml I had to comment out the `terminateWebSessionListener` to give us more time to hit the 'Accept' button. I think we can add it back in once we can figure out how to add the confirmation step to the webflow. I have no experience with spring webflow, so it might take a little bit of time before I can get it integrated.