add mikrotik api support

[0987363]

added to obtain IP from routeros, with a higher priority than API.

add config

  "mikrotik": {
    "enabled": false,
    "server": "http://192.168.88.1:81",
    "username": "admin",
    "password": "",
    "interface": "pppoe-out"
  }

[TimothyYe]

Thanks, it looks good.