moved play_again? method to cli_display
added describe block
Fixed tests to accurately reflect each row
modified play_again? method to return boolean if answer is yes
CLI method for clearing the screen
extracted game over sequence in its own method
Modified play_again? method to returns false if answer is not yes
refactored game_over_sequence and added start_new_game method
Board method for resetting given cell
Computer given a mark depending on the board
Board method checking which mark has won
Board method checking for a draw
minimax algorithm with tests checking various scenarios
Removed unnecessary variable asssignment