Remove or limit dependency to spring

[mdreier-sap]

This application defined an (optional) dependency to the whole Spring framework. Even tough it is optional, some Maven tools see this as an invitation to download the whole spring framework, which severely increases the build time (especially on clean CI builds which do not have a local maven repository cache).

I would suggest to limit the dependency to those parts of the Spring framework which are actually used. If the whole dependency is needed (assuming it is forrunning as a standalone application), maybe this could be refactored into a separate Maven artifact/project.