Fix missing opening tag of the 'div' tag in the project_detail_notifiers.html file

There is a 'div' tag missing an opening tag in the file project_detail_notifiers.html.
Although it is not causing any issues at the moment, it may lead to UI display errors
in the future. We have added the opening tag for this 'div' tag.

Author: hoangpn

promgen/templates/promgen/project_detail_notifiers.html

@@ -9,12 +9,13 @@
 <div class="panel panel-default">
   {% include "promgen/notifier_block.html" with object=project show_edit=1 %}
 </div>
-{% if project.service.notifiers.count %}
+<div>
+  {% if project.service.notifiers.count %}
   <a class="btn btn-default btn-xs" role="button" data-toggle="collapse"
      href="#show-service-senders" aria-expanded="false" aria-controls="collapseExample"
   >
     Show Service Notifiers ({{project.service.notifiers.count}})
   </a>
   {% include "promgen/notifier_block.html" with object=project.service collapse="show-service-senders" %}
-{% endif %}
+  {% endif %}
 </div>