Maven build "sane defaults"

If `mvn` is not explicitly run with `-Psonatype-oss-release`, then the following release-specific configurations are altered to simpler defaults:

1. Javadocs are not generated
2. Source jar is not generated
3. Artifacts are not signed
4. Shaded (complete) jar is not generated
5. OSX application bundle is not generated
6. The `-bootclasspath` option is not passed to javac