Fires once for each bucket returned when listing buckets.
The 'callback' is called when the 'BucketList' event is emited.
The argument 'e' has the following properties:
e.bucketName e.creationDate e.ownerId e.ownerName
This event fires once for each bucket returned when ListBuckets is called.
BucketName reflects the name of the bucket.
CreationDate reflects the bucket's creation date.
OwnerId and OwnerName reflect the Id and display name of the bucket's owner, respectively.