fix: tests run independent of global npm

`npm install` should ensure all the needs required by the application to
execute properly. this removes any additional action needed by the
developer.
chore(config): .DS_Store will not appear on remote
test(Board): should exist and respond to length
test(Board): initialize w. length and empty square
test(Board): #row should return an arr of elements
test(Board): #column returns correct elements
test(Board): interaction tests occur at top-level
test(Board): #diagonal should return correctly
chore(comments): class description and I/O headers
clarify(comment): better wording
refactor(Board): test statement more clear

when reading with 'Array' as the direct object of the sentence it may
mislead developers into thinking that the test is expecting an array.
test(Board): #diagonal returns items based on data
Merge branch 'core-TicTacToeBoard' into develop
chore(config): reduces anxiety while testing

adds --bail flag to unit tests so that they are handled one-by-one