Support for raw JSON in the message

[upperwal]

publish needs a protobuf serialiser with predefined data standard before sending the data to the wire.

There are multiple use cases where dynamic data standards are required and JSON could be a good way of sending this kind of data.

Challenges:

• How will the end user distinguish between JSON and Protobuf message?
• Deserialisation would be an issue if format is not known before. Need to identify it somehow.