Need to add more tests/testing around string sequencing algorithms

[vickumar1981]

The following are the sequencing algorithms which are implemented:

Needleman-Wunsh: https://en.wikipedia.org/wiki/Needleman%E2%80%93Wunsch_algorithm

Smith-Waterman & Smith-Waterman-Gotoh:
https://en.wikipedia.org/wiki/Smith%E2%80%93Waterman_algorithm

Need to add more tests/examples to make sure these implementations are working as expected.

https://github.com/vickumar1981/stringdistance/blob/master/src/test/scala/TestStringDistance.scala#L132