MinIO Sever support

[davidspiola]

I did some debugging regarding MinIO support. As AFAICT, the API handling has changed a bit. To work properly, the bucketName has to be part of the mandatory prefix.

It works again with a minor change in S3Target.php Line 250 and the according prefixes for storage and target. But I can't tell if it breaks Google and AWS server support and wonder what the best way for MinIO support would be? A dedicated Target Class seems a bit much for such a small change.

I'm happy to contribute with some guidance :-)

[dfeyer]

@davidspiola I use this package with Minio in local kubernetes cluster and works pretty fine without hacking the source code.

[kdambekalns]

@davidspiola Any further feedback on this? What versions (MinIO and this package) are involved?