ch5 add tests and solutions

[oldfartdeveloper]

Per issue #79

@p2327 and @oldfartdeveloper are discussing here and here.

[oldfartdeveloper]

@p2327 - I've signed up for adding tests/solutions to chapter 7 (#109). You are welcome to this issue if you want it.

[dvail]

Is anyone currently working this? I'm studying through chapter 5 myself right now, and can open a PR with my solutions once I'm finished.

[milesfrain]

@dvail That would be great. Thanks for checking. I'll assign this task to you so we don't have multiple people working on it simultaneously.