ditto-release-without-central

Skips publishing to Maven central as first step (to use in case artifacts were already published to central, but build failed).

• VERSION: the version to release

1. checkout of latest master codebase
2. changes the version of the codebase to the configured VERSION
3. builds the codebase
   • enforces that no SNAPSHOT versions are used in dependencies
   • runs tests
   • attaches "-sources" artifacts
   • attaches "-javadoc" artifacts
   • signs artifacts with Eclipse CBI "jarsigner-plugin"
4. deploys the built artifacts to:
   • Eclipse Ditto Maven repository
5. creates+pushes a GitHub tag with the specified VERSION