Enable storage replication for V2 and add backfill tool

Fixes #1501

util/backfillreplication.py

@@ -0,0 +1,30 @@
+import logging
+import features
+
+from endpoints.replication import queue_storage_replication
+from data.database import Image, ImageStorage, Repository, User
+
+def backfill_replication():
+  encountered = set()
+  query = (Image.select(Image, ImageStorage, Repository, User)
+                .join(ImageStorage)
+                .switch(Image)
+                .join(Repository)
+                .join(User))
+
+  for image in query:
+    if image.storage.uuid in encountered:
+      continue
+
+    print "Enqueueing image storage %s to be replicated" % (image.storage.uuid)
+    encountered.add(image.storage.uuid)
+    queue_storage_replication(image.repository.namespace_user.username, image.storage)
+
+
+if __name__ == '__main__':
+  logging.basicConfig(level=logging.INFO)
+  if not features.STORAGE_REPLICATION:
+    print "Storage replication is not enabled"
+  else:
+    backfill_replication()
+