Use S3 as static and media storage

TODO

- [ ] Write some documentation for non-AWS, S3-compatible services
- [ ] Make a management command to move existing media to the new S3 bucket
- [ ] See if Nginx can reverse-proxy the S3 bucket in order to keep the files accessible through the domain name

bookwyrm/storage_backends.py

@@ -0,0 +1,11 @@
+from storages.backends.s3boto3 import S3Boto3Storage
+
+class StaticStorage(S3Boto3Storage):
+    location = 'static'
+    default_acl = 'public-read'
+
+
+class ImagesStorage(S3Boto3Storage):
+    location = 'images'
+    default_acl = 'public-read'
+    file_overwrite = False