First attempt at a move to a ActionFilter based policy

[KevM]

This is what I ended up with to get past my issue with the ordering of the AntiForgeryNode in the behavior chain.

This solution is also in the direction of #7. The main problem I have with this PR is that I have not removed the old behavior or behavior node yet because I cannot find a way to approximate the AntiForgeryTokenAttribute behavior because I do not know how to address the ActionFilter in the behavior chain.

        public override void Alter(ActionCall call)
        {
            call.AddBefore(new AntiForgeryNode(Salt));
        }

The action filter is hard to uniquely identify in the action call.