title: Allow Django Admin to change whether a field is required
body: <p>I'd like to be able to change whether the email field is required or not, depending on whether I'm showing a friend or a customer, without having to push to git every time and redeploy. </p>
  
  <p>I have set up a Configuration model for other settings in Django which is configurable from the admin, but unfortunately I'm not able to use any of these settings in other Models or Model Fields, as it causes database errors on migration. </p>
  
  <p>This is my code (it fails because of the migration issue)</p>
  
  <pre><code>class UserForm(forms.ModelForm):
      stake = StakeField()
      email = forms.EmailField(required=getConfig(ConfigData.USER_EMAIL_REQUIRED))
  
      class Meta:
          model = User
          fields = '__all__'
  </code></pre>
  
  <p>Is there another way to set the required/blank setting in either the model, modelform or form which won't cause this issue?</p>
  
  <p><strong>Edit for clarity:</strong></p>
  
  <p>I already have the Configuration AdminModel, but I'm struggling to use this value (True/False) in a ModelForm field without database errors, for a user facing form. </p>