Install git-lfs in CircleCI tests

[namurphy]

The package requires git lfs for large file storage. At present the package is running into an error for CircleCI builds of the documentation because git lfs is not installed. We need to edit the CircleCI test configuration file to make sure that git lfs is installed correctly.

[namurphy]

No longer needed, at least for the time being, since we've dropped git lfs.