title: Override label in Django Forms
body: <p>I have 3 sections with identical fields, except for label on "title" field. 
  For all of them I'm using same Django Form.</p>
  
  <p>In views I have:</p>
  
  <pre><code>def get(self):
      context = self.CONTEXT_CLASS(self.MODEL_CLASS)
      context.messages = self.get_messages()
      context.section1 = InvoiceContentForm()
      context.section2 = InvoiceContentForm()
      context.section3 = InvoiceContentForm()
      self.render_jinja('templates/invoice/add_edit.html', context.as_dict)
  </code></pre>
  
  <p>My form:</p>
  
  <pre><code>class InvoiceContentForm(forms.Form):
  """Form for content of given section in add/edit invoice page."""
  DEFAULT_ATTRS = {'class': 'form-control'}
  
  title = forms.CharField(
      help_text='Title should be up to 24 characters long.',
      label=u'Title',
      required=True,
      widget=FormTextInput(),
  )
  (...)
  </code></pre>
  
  <p>Is there any way I can change title's label on <code>InvoiceContentForm()</code> while assigning it to <code>context.section1 = InvoiceContentForm()</code>?</p>