Added make_response to FlaskView as a class method

I've added the ability to override Flask's `make_response` function by adding a new `make_response` class method to FlaskView.

The motivation is to provide an final and inheritable "decorator-like" function that wraps the view's response.

Decorators are inheritable; however, if a subclass wishes to modify the decorator list, they need to be aware of the parents decorators to do so.

I'm not sure if this function should be an instance function or a class method.  I've created it as a class method; however, I'd be willing to change it to an instance method to provide easier and cleaner subclassing.