multipart/form-data by default

gas/templates/gas/base_form.html

@@ -4,7 +4,7 @@
 {% load form_tags %}
 
 {% block content %}
-    <form action="." method="POST">{% csrf_token %}
+    <form action="." method="POST" enctype="multipart/form-data">{% csrf_token %}
         {% if is_popup %}
             <input type="hidden" name="_popup" value="1">
         {% endif %}