start refactor for game.rb
added available positions for board
added valid_move? to board_controller
fixed ask user for next move test
added test for testing invalid user move
updated test for invalid move
moved display_board into the loop
fixed some wording in game.rb
moved next computer move to game.rb to be at the same level as user move
removed available positions from board_controller.rb
refactor board_controller, not concerned with user side, only displaying symbol as status
refactor board_controller, using clear name
minor fix.