Merge pull request #120 from aisk/us-api-host

change us api server host

Author: wangxiao

lib/utils.js

@@ -181,7 +181,7 @@
     *Use USA avoscloud API service:https://us.avoscloud.com
     */
    AV.useAVCloudUS = function(){
-    AV.serverURL = "https://avoscloud.us";
+    AV.serverURL = "https://us-api.leancloud.cn";
    };
 
   /**