fixed bug: importData return promise

dist/kityminder.core.js

 /*!
  * ====================================================
- * kityminder - v1.4.1 - 2015-07-07
+ * kityminder - v1.4.1 - 2015-07-09
  * https://github.com/fex-team/kityminder-core
  * GitHub: https://github.com/fex-team/kityminder-core.git 
  * Copyright (c) 2015 Baidu FEX; Licensed MIT
@@ -841,7 +841,7 @@ _p[11] = {
                 };
                 // 导入前抛事件
                 this._fire(new MinderEvent("beforeimport", params));
-                return Promise.resolve(protocol.decode(data, this, option)).then(function(json) {
+                return protocol.decode(data, this, option).then(function(json) {
                     minder.importJson(json);
                     return json;
                 });

src/core/data.js

@@ -194,7 +194,7 @@ define(function(require, exports, module) {
             // 导入前抛事件
             this._fire(new MinderEvent('beforeimport', params));
 
-            return Promise.resolve(protocol.decode(data, this, option)).then(function(json) {
+            return protocol.decode(data, this, option).then(function(json) {
                 minder.importJson(json);
                 return json;
             });