First attempt at a move to a ActionFilter based policy

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](https://github.com/DarthFubuMVC/FubuMVC.AntiForgery/blob/master/src/FubuMVC.AntiForgery/AntiForgeryTokenAttribute.cs) behavior because I do not know how to address the ActionFilter in the behavior chain.

```cs
        public override void Alter(ActionCall call)
        {
            call.AddBefore(new AntiForgeryNode(Salt));
        }
```

The action filter is hard to uniquely identify in the action call.