Include cuSPARSE benchmarks

[DanecLacey]

It should be straightforward to essentially carbon-copy the MKL benchmarks, but use cuSPARSE. This is essential for comparisons. @SriramKatta do you want to try to make a cuSPARSE SpMV benchmark?

[SriramKatta]

@DanecLacey yes, I can work on this!