Implement __bytes__ for the Multiaddr class

As per #48 (comment)

Author: ntninja

multiaddr/multiaddr.py

@@ -152,6 +152,8 @@ def to_bytes(self):
         """Returns the byte array representation of this Multiaddr."""
         return self._bytes
 
+    __bytes__ = to_bytes
+
     def protocols(self):
         """Returns a list of Protocols this Multiaddr includes."""
         return MultiAddrKeys(self)