Permanently set the JSON configuration

        Unable to call twice.

def set_json(self, config_json):
        """Permanently set the JSON configuration

        Unable to call twice."""

        if self.configuration_dict is not None:
            raise RuntimeError("Can only set configuration once", self.configuration_dict)

        schema = fetch_config('ConfigurationSchema.json')
        validictory.validate(config_json, schema)

        config_json['name'] = self.name
        config_json['run_number'] = self.run
        config_json['src_dir'] = get_source_dir()
        config_json['data_dir'] = get_data_dir()
        config_json['log_dir'] = get_log_dir()

        self.configuration_dict = config_json