code: public static JavaRDD<List<Writable>> normalize(Schema schema, JavaRDD<List<Writable>> data,
                      List<String> skipColumns) {
          return normalize(schema, data, 0, 1, skipColumns);
      }
docs: Scale all data  0 to 1
  
  @param schema the schema of the data to scale
  @param data   the data to scale
  @return the normalized ata