Fix issue #204: Remove a poorly designed challenge#651

Simon-Stone wants to merge 1 commit intoswcarpentry:mainswcarpentry/python-novice-gapminder:mainfrom

Simon-Stone:FIX_204-remove_local_and_global_variable_use_challengeSimon-Stone/python-novice-gapminder:FIX_204-remove_local_and_global_variable_use_challengeCopy head branch name to clipboard