s3: print out time in UTC format

fix https://github.com/chrislusf/seaweedfs/issues/1297

weed/s3api/filer_multipart.go

@@ -207,7 +207,7 @@ func (s3a *S3ApiServer) listObjectParts(input *s3.ListPartsInput) (output *ListP
 			}
 			output.Parts = append(output.Parts, &s3.Part{
 				PartNumber:   aws.Int64(int64(partNumber)),
-				LastModified: aws.Time(time.Unix(entry.Attributes.Mtime, 0)),
+				LastModified: aws.Time(time.Unix(entry.Attributes.Mtime, 0).UTC()),
 				Size:         aws.Int64(int64(filer2.TotalSize(entry.Chunks))),
 				ETag:         aws.String("\"" + filer2.ETag(entry) + "\""),
 			})

weed/s3api/s3api_bucket_handlers.go

@@ -38,7 +38,7 @@ func (s3a *S3ApiServer) ListBucketsHandler(w http.ResponseWriter, r *http.Reques
 		if entry.IsDirectory {
 			buckets = append(buckets, &s3.Bucket{
 				Name:         aws.String(entry.Name),
-				CreationDate: aws.Time(time.Unix(entry.Attributes.Crtime, 0)),
+				CreationDate: aws.Time(time.Unix(entry.Attributes.Crtime, 0).UTC()),
 			})
 		}
 	}