title: Django error message in class based view
body: <p>Can I change the error message from the model for a class-based view? the following is not working, it always gives the default message from Django.</p>
  
  <p>Model:</p>
  
  <pre><code>class Child(models.Model):
     name = models.CharField(max_length=100, error_messages={ 'blank': 'cannot be blank or null', 'null': 'cannot be blank or null',})
  </code></pre>
  
  <p>view:</p>
  
  <pre><code>class ChildCreate(CreateView):
    model = Child
    fields = '__all__'
    success_url = reverse_lazy('children-list')
  </code></pre>