Flexible configuration and user authentication

- added flexible configuration by 'dictionaries' with sample implementation for file lookups and sql database lookups
- added user authentication based on extended configuration attributes "auth users" and "secrets"
Hint: SessionStatus.AUTHREQ reads username + password. There should be another SessionStatus to request the username without the password for non-auth'ed transmissions
this should use proper logging and throw an exception instead. Right now the error will just be printed to stderr....