combine the user config file with the system config file (if present)

def _config_file():
    """
    combine the user config file with the system config file (if present)
    """
    config = ConfigParser.SafeConfigParser()
    configs = []

    try:
        configs.append(_user_config_file())
    except Exception, e:
        juicer.utils.Log.log_debug(e)

    config.read(configs)
    return config