Adding chunk shape to notebook

@dblodgett, @pnorton, and @rmcd, I wanted your thoughts on this work.

I noticed on a couple of the notebooks in recent merge requests folks were copying Parker's chunk_shape_3d.ipynb and renaming it for getting their chunk sizes. So, I translated the chunk_shape_3D notebook into a Python file and added the argparse module to handle command line arguments. I then add this to the getting chunk size of the template notebook. Check it out and let me know your thoughts.

Further changes could be made by deleting from the "Assessing Data Dimensions" to just before "The Final Chunk Plan" as I think Parker's work supercedes this.