text: Title: [Feature Request] Make DecentralizedAverager resistant to KeyboardInterrupt
  Body: __Update:__ The issue is fixed for the DHT but remains unsolved for DecentralizedAverager.
  
  Currently, if you're running hivemind.DHT in jupyter (or an interactive console), you will sometimes need to hit "interrupt" when prototyping. Unfortunately, KeyboardInterrupt will also be caught by the DHT process and will shutdown that DHT instance.
  
  To reproduce:
  
  ```python
  import time
  import hivemind
  
  
  dht = DHT(start=True)
  
  while True:
      time.sleep(1)
      dht.store('key', 'value', expiration_time=hivemind.get_dht_time() + 999)
      print(end='.', flush=True)
      # [interrupt here via kernel -> interrupt]
      
  # and then check:
  assert dht.is_alive()
  ```
  
  Notes:
  - Whatever fix we implement must still be able to shutdown DHT if it gets deallocated or when calling .shutdown()
  - This problem also applies to DecentralizedAverager (fix or create an issue)