Using custom actions instead of utter_ask templates in forms

[smn-snkl (Simon)]

For example you could do something like this to fill in some variables in your templates:

def request_next_slot(self, dispatcher, tracker, domain):
    """Send customized message"""

    for slot in self.required_slots(tracker):
        if self._should_request_slot(tracker, slot):
            kwargs = {}
            if slot == 'some_slot':
                kwargs.update({"some_template_variable": "some_value"})

            dispatcher.utter_template("utter_ask_{}".format(ask), tracker, **kwargs)

            return [SlotSet(REQUESTED_SLOT, slot)]