Added select avg arr/dep delay to ch08/explore_delays.py
Added select avg arr/dep delay to ch08/explore_delays.py

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