Updated .gitignore to ignore Jupyter files

[danfulton]

Added some globs to the .gitignore file to ignore checkpoint files for Jupyter development environments.

[StoicLoofah]

I have 2 opposing thoughts on this:

1. We don't exclude any other types of dev files e.g. .swp, or the ~ things from emacs
2. I see no downside to adding this

We could say you should put it in .git/info/exclude as a personal preference, but that doesn't help anyone else out.

Any opinions out in the wild on how we should handle this or how other libraries have handled this?

[danfulton]

I usually like to add Jupyter and PyCharm .idea patterns for python heavy projects, but works either way for me. Happy to add it in my own config.

[StoicLoofah]

Can't hurt!