fixes the "RetryOnRenew" lease-renewal needed bug in jclouds, locally, with some guice magic

https://issues.apache.org/jira/browse/JCLOUDS-615 / https://issues.apache.org/jira/browse/BROOKLYN-6

when the former above is fixed properly upstream we can undo this.
This just delegates, rather than captures errors - did I miss something?
Should this be called `DelegatingBlobStore`?