Creates a configuration instance from class :class:`~groundwork.configuration.configmanager.Config` from all
        files in self.files and set the dictionary items as attributes of of this instance.

        :return: Instance of :class:`~groundwork.configuration.configmanager.Config`

def load(self, config_files):
        """
        Creates a configuration instance from class :class:`~groundwork.configuration.configmanager.Config` from all
        files in self.files and set the dictionary items as attributes of of this instance.

        :return: Instance of :class:`~groundwork.configuration.configmanager.Config`
        """
        config = Config()

        for config_file in config_files:
            if not os.path.isabs(config_file):
                config_file = os.path.join(os.getcwd(), config_file)

            self.log.debug("Loading configuration from %s" % config_file)
            d = types.ModuleType('config')
            d.__file__ = config_file
            try:
                with open(config_file) as current_config_file:
                    exec(compile(current_config_file.read(), config_file, 'exec'), d.__dict__)
            except IOError as e:
                e.strerror = 'Unable to load configuration file (%s)' % e.strerror
                raise
            for key in dir(d):
                if key.isupper():
                    if key not in self.invalid_parameters:
                        setattr(config, key, getattr(d, key))
                    else:
                        raise InvalidParameter("%s is not allowed as name for a configuration parameter" % key)
        return config