Update imports on testing files

[Ethan-Arrowood]

Import lines at top of files should be: from main.py import *

[Ethan-Arrowood]

@bgroveben this was opened during a recent call with Repl.it
Do you think you can coordinate with @turbio and complete this?
Ref #8 (comment)

[bgroveben]

@Ethan-Arrowood @turbio will do. I should be able to complete this by Thursday 6/22.

[bgroveben]

@turbio I submitted PR #35 that updates the import statements as well as the unit tests for all of the existing challenges. Hopefully this will make our challenges play nice with the Repl.it platform.