Updated video conferencing sample

Updated multiparty-video-conferencing-client to latest version

Author: Oleksandr Shvetsov

samples/video_conferencing/index.html

@@ -219,7 +219,7 @@ <h5 class="col-md-12 col-sm-12 col-xs-12 push">Add more user (select to add):</h
 <script src="libs/spin.min.js"></script>
 <script src="libs/jquery.blockUI.js"></script>
 <script type="text/javascript" src="https://webrtchacks.github.io/adapter/adapter-latest.js" ></script>
-<script src="libs/quickblox-multiparty-video-conferencing-client-0.8.6.min.js"></script>
+<script src="libs/quickblox-multiparty-video-conferencing-client-0.8.8.min.js"></script>
 <script src="js/video/core.js"></script>
 <script src="js/video/ui_helpers.js"></script>