Support for serialization with jsonpickle

[johannesloibl]

In my application i am serializing the state using jsonpickle. Therefor state_pickler.State needs two additional functions implemented to support this. Maybe you consider adding this to main.

    def __getstate__(self):
        return dict(self)

    def __setstate__(self, state):
        dict.__init__(self, **state)
        self.__dict__ = self