clean up repo for code challenge solutions
boilerplate directory & file structure for testing set up
make_change method tested and working
make_change works for cent amounts up to 100
count_change works and is tested
wrapped change machine api into ChangeMachine class; refactored count_change; removed currency_set from make_change to be available instance-wide
refactored for legibility, sematic naming in count_change; make_change now raises error if argument is 100 or greater.
implemented command line interface for change machine