Add Amazon S3-based screenshot storage.
Review Request #1080 - Created Sept. 16, 2009 and submitted
Add Amazon S3-based screenshot storage. This builds upon my djblets changes to allow people to use django-storages' Amazon S3 storage backend. With this change, admins enter their Amazon AWS access key and secret key, and an S3 bucket name. Uploaded screenshots get saved to S3, and so do the according thumbnails. This change is almost entirely admin site/siteconfig updates for the UI to set the various settings keys that django and django-storages use to select the storage backend and configure it. The only change to non-admin code is to change the screenshot serializer to use the basename of the filename instead of the basename of the path, since not all storage backends implement the path property.
Tested a bunch of screenshot uploads and thumbnailing against my S3 account.