Support raw byte messages/custom serialization

[randomPoison]

The only way of sending messages currently is with the Serialized adapter. While this works for my use case, it doesn't support custom serialization strategies, which is something that we'll likely want at some point. In order to support other serialization strategies, we'll at least need a way to send byte buffers as messages. We should look at UdpSocket::send_dgram and UdpSocket::recv_dgram for an example of how to handle this.

In addition, we should extend Serialized to handle other serialization strategies, while providing a default implementation using bincode. We should look at UdpSocket::framed and UdpCodec for an example of how to set this up.

[randomPoison]

#18 implements sending and receiving raw bytes. The next step is to generalize support for serialization strategies when using Serialized. This would be a good first task for someone to contribute on.