text: Title: p2pd test nat traversal
  Body: ![image](https://user-images.githubusercontent.com/3491902/109007737-89ef7400-76bd-11eb-9320-959a0e20963b.png)
  
  Create a simple setup with 3 nodes where
  - node S1 starts first; it is available publicly; it is a full DHT node
  - nodes A and B are _bootstrap_-ed from S1 and 
  - all nodes use QUIC with ~secio~ tls/noise
  
  TODO:
  - [x] check that nodes A and B can communicate directly if they are **not** behind NAT (localhost-only)
  - [x] check that nodes A and B can communicate if they **are** behind NAT (ping me if you need access to a VM for S1)
  