Rename placeHolderClass to placeholderClass for consistency

Author: Niels Dequeker

source/directives/uiTreeNode.js

@@ -113,11 +113,11 @@
               if (tagName.toLowerCase() === 'tr') {
                 placeElm = angular.element($window.document.createElement(tagName));
                 tdElm = angular.element($window.document.createElement('td'))
-                  .addClass(config.placeHolderClass);
+                  .addClass(config.placeholderClass);
                 placeElm.append(tdElm);
               } else {
                 placeElm = angular.element($window.document.createElement(tagName))
-                  .addClass(config.placeHolderClass);
+                  .addClass(config.placeholderClass);
               }
               hiddenPlaceElm = angular.element($window.document.createElement(tagName));
               if (config.hiddenClass) {

source/main.js

@@ -14,7 +14,7 @@
       nodesClass: 'angular-ui-tree-nodes',
       nodeClass: 'angular-ui-tree-node',
       handleClass: 'angular-ui-tree-handle',
-      placeHolderClass: 'angular-ui-tree-placeholder',
+      placeholderClass: 'angular-ui-tree-placeholder',
       dragClass: 'angular-ui-tree-drag',
       dragThreshold: 3,
       levelThreshold: 30