Issue title: basicr3 (ошибка питона)
 Issue body: При запуске
Exception in thread zeroconf-ServiceBrowser_eWeLink_100090a12f._ewelink._tcp.local.:
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/threading.py", line 926, in _bootstrap_inner
    self.run()
  File "/usr/local/lib/python3.7/site-packages/zeroconf/__init__.py", line 1483, in run
    handler(self.zc)
  File "/usr/local/lib/python3.7/site-packages/zeroconf/__init__.py", line 1423, in <lambda>
    zeroconf=zeroconf, service_type=self.type, name=name, state_change=state_change
  File "/usr/local/lib/python3.7/site-packages/zeroconf/__init__.py", line 1301, in fire
    h(**kwargs)
  File "/usr/local/lib/python3.7/site-packages/zeroconf/__init__.py", line 1400, in on_change
    listener.update_service(*args)
  File "/config/custom_components/sonoff/__init__.py", line 313, in update_service
    if self._seq == properties['seq']:
KeyError: 'seq'

.sonoff.json
{"100090a12f":{"settings":{"opsNotify":0,"opsHistory":1,"alarmNotify":1,"wxAlarmNotify":0,"wxOpsNotify":0,"wxDoorbellNotify":0,"appDoorbellNotify":1},"group":"","online":true,"shareUsersInfo":[],"groups":[],"devGroups":[],"_id":"5e53ac177a1b050008962a32","name":"Stairs light","type":"10","deviceid":"100090a12f","apikey":"4cbe5adf-f38c-4756-ae5a-3cdf2e0e2d23","extra":{"extra":{"uiid":1,"description":"20190508006","brandId":"5c4c1aee3a7d24c7100be054","apmac":"d0:27:01:21:3f:af","mac":"d0:27:01:21:3f:ae","ui":"单通道插座","modelInfo":"5c700fd5cc248c47441fd24a","model":"PSF-BD1-GL","manufacturer":"深圳松诺技术有限公司","chipid":"00ABD2EA","staMac":"DC:4F:22:AB:D2:EA"},"_id":"5cd39271cbfd57f5aa923b34"},"createdAt":"2020-02-24T10:57:27.994Z","__v":0,"onlineTime":"2020-03-09T09:44:10.411Z","params":{"version":8,"sledOnline":"on","switch":"off","fwVersion":"3.0.0","rssi":-47,"staMac":"DC:4F:22:AB:D2:EA","startup":"off","init":1,"pulse":"off","pulseWidth":500},"ip":"116.69.203.115","location":"","tags":{"m_2d23_dm_a":"on"},"deviceStatus":"","offlineTime":"2020-03-09T08:56:06.272Z","sharedTo":[],"devicekey":"df30633a-b05a-4afd-bce8-31ee413ae7b2","deviceUrl":"https://eu-api.coolkit.cc/api/detail/5c700fd5cc248c47441fd24a_en.html","brandName":"SONOFF","showBrand":true,"brandLogoUrl":"https://eu-ota.coolkit.cc/logo/Q4RJzznuKEeDgFXbgyS9OClbyEDR7gXd.png","productModel":"BASIC","devConfig":{},"uiid":1}}

Включение/выключение работает, но состояние не изменяется (при включении переходит на 1-2сек во вкл а потом опять выкл)
 Comments: 
 Comment 0: А обновления прошивки на устройство нет в приложении ewelink?
 Comment 1: Было, все заработало, спасибо
{'source': 'GithubIssues', 'repo_name_with_owner': 'AlexxIT/SonoffLAN', 'issue_id': 577917394, 'repo_stars': 1829.0}