title: .NET Core, SignalR 2 serialization (DateTime)
body: <p>How configure datetime format serialization in SignalR 2 (2.2.1)</p>
  
  <p>Because output json with datetime can be with UTC and without UTC in one response</p>
  
  <p>"dateTime":"2017-02-17T20:27:04.9225787+02:00"</p>
  
  <p>"dateTime":"2017-02-17T20:00:10.1540101"</p>