pooling update handlers, add overlay bot module

bots/templates/cabinet/bots/bot_form.html

@@ -7,7 +7,7 @@
 {% endblock %}
 
 {% block content %}
-    <form action="" method="post" class="card">
+    <form action="" method="post" class="card" enctype="multipart/form-data">
         {% csrf_token %}
         <header class="card-header">
             <h2 class="card-title">{% if feed %}Bot "{{ feed.title }}" configuration{% else %}New bot{% endif %}</h2>