Support bucket versioning (#9377)

- Implement a new xl.json 2.0.0 format to support,
  this moves the entire marshaling logic to POSIX
  layer, top layer always consumes a common FileInfo
  construct which simplifies the metadata reads.
- Implement list object versions
- Migrate to siphash from crchash for new deployments
  for object placements.

Fixes #2111

cmd/bucket-encryption.go

@@ -55,5 +55,6 @@ func validateBucketSSEConfig(r io.Reader) (*bucketsse.BucketSSEConfig, error) {
 	if len(encConfig.Rules) == 1 && encConfig.Rules[0].DefaultEncryptionAction.Algorithm == bucketsse.AES256 {
 		return encConfig, nil
 	}
+
 	return nil, errors.New("Unsupported bucket encryption configuration")
 }