Maven gatekeeping
Maven gatekeeping

- removed maven-site-plugin, as it is not used
- updated plugins:
  io.fabric8:docker-maven-plugin ..................... 0.21.0 -> 0.24.0
  maven-javadoc-plugin ............................... 2.10.4 -> 3.0.0

marcelmay/hadoop-hdfs-fsimage-exporter,marcelmay/hadoop-hdfs-fsimage-exporter