FileNotFoundError with data download utility

[rychallener]

When installing ExoCTK, I used the exoctk.utils.download_exoctk_data() function to fetch the data and encountered a FileNotFoundError on groups_integrations.tar.gz. I think the problem is that this file is listed twice in the DATA_URLs dictionary in utils.py, so the tar file gets uncompressed, deleted, and then the function looks for it again.