title: __init__() got an unexpected keyword argument 'required'
body: <p>For some reason, Django is not letting pass the parameter <code>required=False</code> to my form fields.</p>
  
  <p>This is my form:</p>
  
  <pre><code>class InstrumentSearch(forms.ModelForm): 
      groups = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple, required=False)
      time = forms.TimeInput(required=False)
      date = forms.DateField(required=False)
      notes = forms.TextInput(required=False)
  </code></pre>
  
  <p>The error is on the line</p>
  
  <pre><code>time = forms.TimeInput(required=False)
  </code></pre>
  
  <p>According to the <a href="https://docs.djangoproject.com/en/dev/ref/forms/fields/#required" rel="nofollow">Django Documentation here</a>, this should absolutely work.</p>