Default filter needs to Ignore chains without symmetrical models

[Josh Arnold]

The FubuContinuation does a relaxed search so if you have an action call like:

post_account_create(CreateAccount input)

But your corresponding GET isn't using the same model:

get_account_create(CreateAccountInput request)

You effectively get a StackOverflow when validation fails:
https://github.com/DarthFubuMVC/fubuvalidation/blob/master/src/FubuMVC.Validation/ValidationActionFilter.cs#L46