Added missing jQuery binding for the ack extension.
<script type="text/javascript" src="../../js/cometd/ReloadExtension.js"></script>
<script type="text/javascript" src="https://code.jquery.com/jquery-3.2.1.js"></script>
<script type="text/javascript" src="../../js/jquery/jquery.cometd.js"></script>
+ <script type="text/javascript" src="../../js/jquery/jquery.cometd-ack.js"></script>
<script type="text/javascript" src="../../js/jquery/jquery.cometd-reload.js"></script>
<script type="text/javascript" src="chat.js"></script>
<script type="text/javascript">
