Add a new RadosGW storage engine. Allow engines to distinguish not only between those that can support direct uploads and downloads, but those that support doing it through the browser. Rename resumeable->resumable.

storage/__init__.py

@@ -1,5 +1,5 @@
 from storage.local import LocalStorage
-from storage.cloud import S3Storage, GoogleCloudStorage
+from storage.cloud import S3Storage, GoogleCloudStorage, RadosGWStorage
 from storage.fakestorage import FakeStorage
 from storage.distributedstorage import DistributedStorage
 
@@ -8,6 +8,7 @@ STORAGE_DRIVER_CLASSES = {
   'LocalStorage': LocalStorage,
   'S3Storage': S3Storage,
   'GoogleCloudStorage': GoogleCloudStorage,
+  'RadosGWStorage': RadosGWStorage,
 }