Corners and intersection fixed in the board

Instead of forward and backward slash in the corners, and Pipe in the intersections, I have replaced with corner characters and '+' for intersection. 

Board looks much better.
![bash2048-screenshot](https://cloud.githubusercontent.com/assets/1309805/3157986/31f860ca-eafd-11e3-99d0-1007f7e785ab.png)