Ensure configuration property is absent in /usbkey/config

    name : string
        name of property

def config_absent(name):
    '''
    Ensure configuration property is absent in /usbkey/config

    name : string
        name of property

    '''
    name = name.lower()
    ret = {'name': name,
           'changes': {},
           'result': None,
           'comment': ''}

    # load configuration
    config = _load_config()

    if name in config:
        # delete property
        ret['result'] = True
        ret['comment'] = 'property {0} deleted'.format(name)
        ret['changes'][name] = None
        del config[name]
    else:
        # we're good
        ret['result'] = True
        ret['comment'] = 'property {0} is absent'.format(name)

    # apply change if needed
    if not __opts__['test'] and ret['changes']:
        ret['result'] = _write_config(config)

    return ret