Add fallback for uncrispified forms where form.attrs were not set

It is not necessarily a complete and/or appropriate fallback for forms that are originally non-crispy. This is in ulikely unforeseen cases where for some reason Django widget can not be rendered as a foundation-5/field.html template without loosing some field data.
To sum it up: it should be generic enough for forms that are originally non-crispy but it is not a given. So if this template is to be reused by non-crispy forms (in contrast to uncrispified forms), the rendering of forms should be properly tested.

python/nav/web/templates/custom_crispy_templates/_form_content.html

@@ -21,5 +21,7 @@
     {% endif %}
   {% endblock form_fields %}
 {% else %}
-  {{ form }}
+  {% for field in form %}
+    {% show_field field %}
+  {% endfor %}
 {% endif %}