fixed lubusy

src/lubusy.js

                     templateError: "luticate-error.html"
                 };
 
-                var o = $scope.luBusy();
-                if (o != null) {
-                    angular.extend(options, o);
-                }
-
                 $scope.update = function()
                 {
+                    var o = $scope.luBusy();
+                    if (o != null) {
+                        if (typeof o == 'string') {
+                            options.group = o;
+                        }
+                        else {
+                            angular.extend(options, o);
+                        }
+                    }
+
                     var loaders = luticatePromises.getLoadersGroup(options.group);
                     $scope.isLoading = false;
                     if (loaders != null) {