fix for #950

[FrankHossfeld]

This PR fixes the issue #950 & #227.

Changes:

• add a dependency management to the parent pom
• add a plugin management to the parent pom
• remove all version-tags from dependencies that are managed inside the dependencyManagement and plugins that are managed inside the pluginManagement in the child pom (library & validator & cli)
• remove the maven-shade-plugin (library-module-pom)
• remove the maven-shade-plugin (validator-module-pom)
• add main class in the maven-shade-plugin of the cli pom
• add two dependencies to avoid the CNFE while running the cli (Uber-Jar - Warum? #227)

After merging, no shaded library will be create anymore for the library- and the validator-module.

[jstaerk]

I have become cautious with changes in the POM, is it OK when I merge after the next release and would you be available to release the version after the next one together? We would do a ~1h online meeting so that we can interactively either correct or roll back changes. I did the same with the @langfr 's POM changes and that was super helpful, so far the maven central release process was not very stable towards ... unexpected changes (which could not be tested in advance anyway).