Add flag to list blob metadata to list blob command

Presently this command only lists blob names. It should also offer a --details flag, which ideally would be machine-parsable. Current output for BlobStore.blobMetadata().toString():

[type=BLOB, id=null, name=0008a570cc5fb0fcc0aa05bf37436ddb, location=

{scope=REGION, id=us-standard, description=us-standard, parent=aws-s3, iso3166Codes=[US]}

, uri=https://cloud-testing.s3.amazonaws.com/0008a570cc5fb0fcc0aa05bf37436ddb, userMetadata={}]

and for BlobStore.blobMetadata().getContentMetadata().toString():

[contentDisposition=null, contentEncoding=null, contentLanguage=null, contentLength=1, contentMD5=[-43, 39, -54, 7, 77, 65, 45, -99, 15, -4, -124, 72, 114, -60, 96, 60], contentType=application/unknown, expires=null]

This output is hard to parse and injurious to the human spirit.