Minor enhancements
- Enhance the handling of MDN processing and asociated resend handling to provide moer reliable error handling.
- Enhance the Disposition-Notification-Options handler to properly support the standard.
- Use the LTS releases of Java for testing
- Use a SQL-92 compliant SQL format for accessing the database.
- Deprecate the WebUI app and the Rest API in preparation for implementing as a a wrapper project that provides the web server to support the API.