Merge in GraSPI

[wd15]

Attempt to merge GraSPI into PyMKS

• create prototype cython build for graspi, @owodo, https://github.com/owodolab/graspi/blob/master/setupGraspiCython.py
• nix build for graspi, @wd15, owodolab/graspi#1
• merge the repositories on a branch, @wd15, https://github.com/wd15/pymks/commits/merge-with-graspi
• create file structure for graspi in pymks
• amend setup.py to include graspi build
• nix builds for pymks
• ensure test case runs
• create function in pymks that uses graspi
• create API documentation
• generate PR to test everything
• generate small notebook example
• conda build
• work with dask
• work in a Scikit-learn pipeline

[wd15]

This is done. We have graspi as a module now