message: add instance of CBOR for Addr
diff: @@ -297,6 +297,11 @@ impl fmt::Display for Addr {
  fmt::Display::fmt(&self.0, f)
  }
  }
  +impl cbor::ToCBOR for Addr {
  + fn encode(&self, buf: &mut Vec<u8>) {
  + self.0.encode(buf)
  + }
  +}
  impl Addr {
  pub fn new(addr_type: AddrType, spending_data: &SpendingData, attrs: &Attributes) -> Addr {
  /* CBOR encode + HASH */
  