message: Report two versions supported via VersionNegotiation packet
diff: @@ -320,7 +320,8 @@ impl PacketBuilder {
  encoder.encode(&[0; 4]); // Zero version == VN.
  encoder.encode_vec(1, dcid);
  encoder.encode_vec(1, scid);
  - encoder.encode_uint(4, QuicVersion::default().as_u32());
  + encoder.encode_uint(4, QuicVersion::Draft27.as_u32());
  + encoder.encode_uint(4, QuicVersion::Draft28.as_u32());
  // Add a greased version, using the randomness already generated.
  for g in &mut grease[..4] {
  *g = *g & 0xf0 | 0x0a;
  @@ -1016,8 +1017,8 @@ mod tests {
  const SAMPLE_VN: &[u8] = &[
  0x80, 0x00, 0x00, 0x00, 0x00, 0x08, 0xf0, 0x67, 0xa5, 0x50, 0x2a, 0x42, 0x62, 0xb5, 0x08,
  - 0x83, 0x94, 0xc8, 0xf0, 0x3e, 0x51, 0x57, 0x08, 0xff, 0x00, 0x00, 0x1c, 0x0a, 0x0a, 0x0a,
  - 0x0a,
  + 0x83, 0x94, 0xc8, 0xf0, 0x3e, 0x51, 0x57, 0x08, 0xff, 0x00, 0x00, 0x1b, 0xff, 0x00, 0x00,
  + 0x1c, 0x0a, 0x0a, 0x0a, 0x0a,
  ];
  #[test]
  