Add harmonic search algorithm

[SimonBlanke]

This would add the harmonic search algorithm to the collection of optimizers. I was not successful in accessing the original paper:
"Geem, Z. W., Kim, J. H., & Loganathan, G. V. (2001). A new heuristic optimization algorithm: harmony search."

I found the paper Harmony Search as a Metaheuristic Algorithm instead. This provides a great explanation of the algorithm.