picture message

{
   "receiver": "01234567890A=",
    "min_api_version": 1,
   "sender":
   {
       "name": "John McClane",
       "avatar": "http://avatar.example.com"
   },
   "tracking_data": "tracking data",
    "type": "picture",
   "text": "Photo description",
   "media": "http://www.images.com/img.jpg",
   "thumbnail": "http://www.images.com/thumb.jpg"
}