JCLOUDS-458:Added Blobstore Abstraction

JCLOUDS-458:Added Blobstore Abstraction
Minor Changes testCopyUrl
You don't need to extend this in `MultipartUploadStrategy`; it does not provide any methods or non-static fields to inherit.  Once jclouds/jclouds#512 goes in, Checkstyle will complain about this anti-pattern.