api: ListObjectsV2 response should be validated strictly. (#721)
api: ListObjectsV2 response should be validated strictly. (#721)

This is not a bug as such but an added validation so
that our code doesn't go into an infinite loop when
the S3 server doesn't support `list-type=2`

Fixes #719
harshavardhana/minio-go,minio/minio-go