FinalHandler always uses OK as reasonPhrase if non previously set

[nesl247]

If an error makes it to handleError, without a reasonPhrase, it will always be OK. This is because when calling withStatus, it is passing getReasonPhrase which checks if there is one set, and if not uses it from the current statusCode. Of course statusCode is 200 at that time because it's the default in the constructor.

[michaelmoussa]

I believe #52 will resolve this, @nesl247 /cc @weierophinney