implement end to end example

[dimitarg]

Implement an example web app which showcases usage of sane-dbc. Data model should be something simple but realistic. Can be for example a user management service, providing endpoints for login, logout, creation of user, assignment of user/s to groups, and storage of user preferences.

Web app could be implemented with a variety of technologies, so that the user can pick up the example with the technology they are most familliar with. Possible variants:

• Servlet
• Servlet async
• Undertow
• Spring Boot
• Cletty