add delete and options methods to CORS whitelist (#3589)

cmd/generic-handlers.go

@@ -253,7 +253,7 @@ type resourceHandler struct {
 func setCorsHandler(h http.Handler) http.Handler {
 	c := cors.New(cors.Options{
 		AllowedOrigins: []string{"*"},
-		AllowedMethods: []string{"GET", "HEAD", "POST", "PUT"},
+		AllowedMethods: []string{"GET", "HEAD", "POST", "PUT", "DELETE", "OPTIONS"},
 		AllowedHeaders: []string{"*"},
 		ExposedHeaders: []string{"ETag"},
 	})