Looks for any MACH9_ prefixed environment variables and applies
        them to the configuration if present.

def load_environment_vars(self):
        """
        Looks for any MACH9_ prefixed environment variables and applies
        them to the configuration if present.
        """
        for k, v in os.environ.items():
            if k.startswith(MACH9_PREFIX):
                _, config_key = k.split(MACH9_PREFIX, 1)
                self[config_key] = v