RhodeCode CE/EE

Original impl of social auth had a special callback_url as a readonly fields. Those are now missing, and it's hard to configure the plugins without knowing what is the callback url.

            {
                "name": "callback_url",
                "validator": None,
                "type": "readonly",
                "description": "Callback URL for the provider",
                "default": self.callback_url(),
                "formname": "Callback URL"
            }

That was the option used. I think there's could be some problems with the callback_url