Pulp

Pulp users should be able to configure S3 as the storage backend for their Pulp data. The backend needs to be provided by the django-storages[0] python package. This should be an optional dependency for pulpcore that will be installed by users that want to use S3 as the storage backend.

The content app needs to be updated to recognize when the storage backend is S3. In immediate download use cases, the content app needs to redirect requests to the S3 URL stored on the Artifact. In the 'on demand' use cases, the content app needs to stream the artifact to the client and then save the Artifact. The S3 storage backend should handle the uploading of the file to S3 as part of the save.

Documentation needs to be added to let users know how to configure S3 as the storage backend.

[0] https://django-storages.readthedocs.io/en/latest/backends/amazon-S3.html