code: public static String getDockerItDir() {
          final String dockerItDir = targetDir().getAbsolutePath() + "/docker-it/";
          final File dir = new File(dockerItDir);
          dir.mkdirs();
          return dockerItDir;
      }
docs: Directory for placing temp files for building images.
  Every class should create some subdirectory for their needs.
  Path ends with '/';