Hook responseAlter

I've created a hook called ```responseAlter``` that allows for a last change on the payload being answered to a request. It is proving to be very useful on my project. This hook receives the *payload* object (which will by default have at least ```status.code``` data), the *request* object, and the *response* object. Only the *payload* object should be modified, as modifying the *request* or the *response* should cause for no changes because this is really a last call and all processes have already taken place. They serve only as informative objects.
Is call(this, ...) really necessary? Doesn't this just add another indirection?

Sorry for just commenting on this now.