[Roadmap] SITreg using the SAP Cloud Application Programming Model

[gregorwolf]

• Project setup
• Invite contributors
• Add get started to readme
• Build admin service containing all entities including tests and business logic
• Implement organizer service with business logic and tests
• Add authentication
• Implement participant service with business logic and tests
• Implement public service with business logic and tests
• Implement receptionist service with business logic and tests