Cloud providers do not return Metadata from the stored object

[nover]

As discovered when working with #33 it seems like the cloud storage providers (and the local one too) does not return the Metadata:dictionary<string, string> stored on the object in the BlobDescriptor when calling GetBlobDescriptor*.

I believe this is a bug as it effectively renders callers unable to retrieve stored metadata on their objects.

[optyingale]

Hi @ericgreenmix or @jarroda or @nover,
Could someone please have a look at my pull request?

At the moment it seems to be failing tests because of missing connection string in the test

[ericgreenmix]

I will figure out what is going on with the tests and get this merged in as soon as I get time. Thanks!