Concept for database shema evolution

[luechtdiode]

The actual setup for the database is not scaleable for later schema evolution. The init.sql script is only applied on initial startup of the system, when no database exists.

Some suggestions:

• https://www.npmjs.com/package/node-flywaydb
• https://dev.to/endykaufman/create-a-database-for-the-application-and-create-first-migration-via-flyway-4hjb
• https://github.com/domdinnes/node-flyway