- Create system message API helper
https://github.com/openpeer/opios-production/issues/140

- "Composing" struct to JSON
https://github.com/openpeer/opios-production/issues/124

- JSON to "Composing" struct
https://github.com/openpeer/opios-production/issues/125

- Add "replacedMessageID" to API
https://github.com/openpeer/opios-production/issues/136

- Add "read" status to message delivery enum
https://github.com/openpeer/opios-production/issues/139

- Implement helper composing API
https://github.com/openpeer/opios-production/issues/151