Changed logic of space values, refactored get_corner_move and added side logic

Found an edge case where choosing the middle first would allow a player
to win, thus I put the value of a corner higher.

Changed get_corner_move to get_move, this function now has a string that
tells the function if its a side or corner move, this includes a new
get_open_sides method that determines the sides we can choose from.
Implemented some final logic changes and function refactors

implemented final game logic, moved game play logic to a function, moved
game winning print logic to its own function.

Also corrected some of my code styling and added some more comments.
Code cleanup, removed debugging print commands
No longer draw the board twice when the computer goes first and corrected flawed logic on get_board_moves_left