This includes using `''` instead of `None` in some cases where an empty
string conveys 'nothing' equally well as `None`; in such cases keeping the
type the same rather than switching to another type is preferred.
This uses Reqests-Cache, which should be installed on the PYTHONPATH or
provided as a wheel in blender_cache/requests_cache-*.whl. In the latter
case, it'll be automatically added to sys.path.
