Add a configuration section for authentication

Context

JWT token-based authentication, as introduced at !128 (merged), has different parameters:

• Method: type of authorization method.
• Secret: secret or key to be used for validating request.
• Algorithm: crytographic algorithm used to encode tokens.

Task Description

• Agree on a YAML configuration section for authentication.
• Parse and handle that new configuration section.

Acceptance Criteria

All the parameters above can be driven via the server configuration file.