Copied Spark feature extraction script from chapter 7 to chapter 8
Copied Spark feature extraction script from chapter 7 to chapter 8

naoyak/Agile_Data_Code_2,naoyak/Agile_Data_Code_2,rjurney/Agile_Data_Code_2,rjurney/Agile_Data_Code_2,naoyak/Agile_Data_Code_2,rjurney/Agile_Data_Code_2,naoyak/Agile_Data_Code_2,rjurney/Agile_Data_Code_2