s3: support object tagging

* GetObjectTagging
* PutObjectTagging
* DeleteObjectTagging

weed/s3api/s3err/s3api_errors.go

@@ -61,6 +61,7 @@ const (
 	ErrInternalError
 	ErrInvalidCopyDest
 	ErrInvalidCopySource
+	ErrInvalidTag
 	ErrAuthHeaderEmpty
 	ErrSignatureVersionNotSupported
 	ErrMalformedPOSTRequest
@@ -188,6 +189,11 @@ var errorCodeResponse = map[ErrorCode]APIError{
 		Description:    "Copy Source must mention the source bucket and key: sourcebucket/sourcekey.",
 		HTTPStatusCode: http.StatusBadRequest,
 	},
+	ErrInvalidTag: {
+		Code:           "InvalidArgument",
+		Description:    "The Tag value you have provided is invalid",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 	ErrMalformedXML: {
 		Code:           "MalformedXML",
 		Description:    "The XML you provided was not well-formed or did not validate against our published schema.",