Payload format and content type

[andsel]

Allow the payload format (binary, text) and a MIME style content type to be specified when a message is published. These are forwarded on to the receiver of the message.

• handle payload format indicator property Payload format verification and content type properties handling #826
  • write a test to verify payload format indicator property is forwarded as it is by the broker [MQTT-3.3.2-4]
  • if the payload format indicator verify the payload is UTF-8, if not, send PUBACK or PUBREC with 0x99 reason code (Payload format invalid)
• verify Content type is UTF-8 and close the connection if not (it's a protocol error)
  • test the content-type is forwarded as opaque
  • [ ] test that if content-type is not in UTF-8 then the connection is dropped (This is hard to write a test because all MQTT client accepts a String, and also setting a bad byte sequence to a String, when it's created from raw bytes, that string quotes those chars transforming in ? chars, loosing the original byte sequence in phase of sending a publish)

[andsel]

Closed by#826