let itunes link works in wechat

Author: cgcgbcbc

app/index.html

@@ -59,7 +59,7 @@ <h1 id="download">TUNet</h1>
                   <a class="btn btn-primary btn-lg" href="latest">下载 Android 版本 &raquo;</a>
                 </p>
                 <p>
-                  <a href="https://itunes.apple.com/cn/app/itunet-qing-hua-xiao-yuan/id944698141?mt=8">
+                  <a href="//tunet.lab.mu/itunes">
                     <img width="193px" src="images/App_Store_Badge.svg" />
                   </a>
                 </p>