JSON-RPC 2.0 websocket response format

Format of updates in events websocket endpoint was changed to JSON-RPC 2.0 standard.

Now updates looks like:

{
    "jsonrpc":"2.0",
    "result":{
        "session":"session",
        "update":{
            "_":"updateUserStatus",
            "user_id":64459193,
            "status":{
                "_":"userStatusOnline",
                "expires":1579128837
            }
        }
    },
    "id":null
}