JCLOUDS-458:Added Blobstore Abstraction

JCLOUDS-458:Added Blobstore Abstraction
Minor Changes testCopyUrl
What specifically yields a 503 error, a put followed by a get of the same object?  I found this reference:

https://developers.google.com/storage/docs/concepts-techniques#object-updates

Perhaps we need to add a GCS specific fallback and change its retry time to 1 second?