Fix for issue #12 - detection issues

This problem was caused by a bug that ignored pieces in the count to 4 if they immediately followed a piece of the opposite color. Since the counting happens from the bottom and the right, the bug would not register wins if an opponent was directly below or to the right of the four-in-a-row.

The code has been refactored to find this case and set the count to 1 instead of 0. See screenshot of a fixed game:

![connect4](https://cloud.githubusercontent.com/assets/4370652/2992636/5fa3e112-dc97-11e3-841c-c410e7be69e9.png)