Fixed #19733 - deprecated ModelForms without 'fields' or 'exclude', and added '__all__' shortcut

This also updates all dependent functionality, including modelform_factory
 and modelformset_factory, and the generic views `ModelFormMixin`,
 `CreateView` and `UpdateView` which gain a new `fields` attribute.

docs/ref/class-based-views/generic-editing.txt

@@ -110,6 +110,7 @@ CreateView
 
         class AuthorCreate(CreateView):
             model = Author
+            fields = ['name']
 
 UpdateView
 ----------
@@ -152,6 +153,7 @@ UpdateView
 
         class AuthorUpdate(UpdateView):
             model = Author
+            fields = ['name']
 
 DeleteView
 ----------

docs/ref/class-based-views/mixins-editing.txt

@@ -116,6 +116,18 @@ ModelFormMixin
         by examining ``self.object`` or
         :attr:`~django.views.generic.detail.SingleObjectMixin.queryset`.
 
+    .. attribute:: fields
+
+        .. versionadded:: 1.6
+
+        A list of names of fields. This is interpreted the same way as the
+        ``Meta.fields`` attribute of :class:`~django.forms.ModelForm`.
+
+        This is a required attribute if you are generating the form class
+        automatically (e.g. using ``model``). Omitting this attribute will
+        result in all fields being used, but this behaviour is deprecated
+        and will be removed in Django 1.8.
+
     .. attribute:: success_url
 
         The URL to redirect to when the form is successfully processed.