[#125] Handle negative Content-Length on put

Add computing actual object size during calculating hash on put.
Use this actual value to save in tree and cache

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

api/handler/attributes.go

@@ -17,7 +17,7 @@ type (
 	GetObjectAttributesResponse struct {
 		ETag         string       `xml:"ETag,omitempty"`
 		Checksum     *Checksum    `xml:"Checksum,omitempty"`
-		ObjectSize   int64        `xml:"ObjectSize,omitempty"`
+		ObjectSize   uint64       `xml:"ObjectSize,omitempty"`
 		StorageClass string       `xml:"StorageClass,omitempty"`
 		ObjectParts  *ObjectParts `xml:"ObjectParts,omitempty"`
 	}