Updated Smith-Waterman example.

Added a README and a run_test.sh script like those included for Cholesky. The implementation is now roughly equivalent to the Smith-Waterman example included in the OCR distribution (https://github.com/01org/ocr/tree/master/examples/smith-waterman). This implementation has the advantage of not crashing on large inputs because it only keeps the bottom and right edges of tiles (rather than entire tiles) in the item collections.