Use something smarter than `Show/Read` for the websockets protocol

I just tried to use `Data.Serialize` with generic deriving, but am stuck. While `Network.WebSockets` (the server side) has no problems sending binary data (as a `ByteString`) over the wire, the corresponding support in ghcjs, at , seems to be shaky. I might get a `Blob` out, but I do not see how to get a `ByteString` out.

I think I was at this point before, so I record this here.

Either I need to figure out how to work with `ByteString` in GHCJS, or use a different serialization library which targets `Data.Text`.