Respect IPYTHONDIR and JUPYTER_CONFIG_DIR

Thank you very much for making a sane application that respects the XDG specs. That being said, due to ipython/jupyter deciding to abandon it, could support of IPYTHONDIR and JUPYTER_CONFIG_DIR be implemented? I have those env vars set but nteract seems to ignore them.

[stale]

This issue hasn't had any activity on it in the last 90 days. Unfortunately we don't get around to dealing with every issue that is opened. Instead of leaving issues open we're seeking to be transparent by closing issues that aren't being prioritized. If no other activity happens on this issue in one week, it will be closed.
It's more than likely that just by me posting about this, the maintainers will take a closer look at these long forgotten issues to help evaluate what to do next.
If you would like to see this issue get prioritized over others, there are multiple avenues 🗓:

• Ask how you can help with this issue 👩🏿‍💻👨🏻‍💻
• Help solve other issues the team is currently working on 👨🏾‍💻👩🏼‍💻
• Donate to nteract so we can support developers to work on these features and bugs more regularly 💰🕐

Thank you!

[captainsafia]

Migrating this to the jupyter-paths repo since this changes will likely need to happen there.

Also marking it as new contributor friendly/help wanted.