Fix for #1671 - Adding [FromHeader] attribute

As discussed, we don't want the *full* set of smarts that collection model binder has here. We also don't want to do things the way collection model binder works. 

I think this code is going to diverge **more** once we agree on a strategy for converting values to strongly-typed values from headers. I'll open an item in there and put a footnote in about refactoring this with collection model binder.