Add more python essentials exercises

[mmcky]

@kp992 would you please review 40eedfd and let me know what you think.

I have been putting together a couple of new notebooks that are tutorials mixed with exercises.

I am thinking of adding this as Day 02 exercises instead of the linear algebra notebook (and moving that to day 03). I think we need a slower build up in exercise difficulty.

[kp992]

@mmcky This sounds like a nice idea. Thank you adding the notebook. It looks great!