title: How could one disable new account creation with django-allauth, but still allow existing users to sign in?
body: <p>We've been running a site for a while which uses <a href="https://github.com/pennersr/django-allauth" rel="noreferrer"><code>django-allauth</code></a> for authentication using any of:</p>
  
  <ul>
  <li>Traditional email-based sign-up</li>
  <li>Google login</li>
  <li>Twitter login</li>
  <li>Facebook login</li>
  </ul>
  
  <p>... but now we want to stop anyone creating a new account, while still allowing people who've previously created an account using any of those methods to be able to log in. Is there a setting that will let us do this? It's not clear to me that any of <a href="http://django-allauth.readthedocs.org/en/latest/configuration.html" rel="noreferrer">these documented settings</a> would allow us to configure that.</p>
  
  <p>The current settings relating to django-allauth are:</p>
  
  <pre><code>INSTALLED_APPS = (
      'django.contrib.auth',
      ...
      'allauth',
      'allauth.account',
      'allauth.socialaccount',
      'allauth.socialaccount.providers.google',
      'allauth.socialaccount.providers.facebook',
      'allauth.socialaccount.providers.twitter',
      ...
  )
  
  AUTHENTICATION_BACKENDS = (
      # Needed to login by username in Django admin, regardless of `allauth`
      "django.contrib.auth.backends.ModelBackend",
      # `allauth` specific authentication methods, such as login by e-mail
      "allauth.account.auth_backends.AuthenticationBackend",
  )
  
  SOCIALACCOUNT_PROVIDERS = {
      'google': {'SCOPE': ['https://www.googleapis.com/auth/userinfo.profile'],
                 'AUTH_PARAMS': {'access_type': 'online'}},
      'facebook': {'SCOPE': ['email',]},
  }
  
  LOGIN_REDIRECT_URL = '/'
  
  ACCOUNT_EMAIL_VERIFICATION = "mandatory"
  ACCOUNT_EMAIL_REQUIRED = True
  ACCOUNT_USERNAME_REQUIRED = True
  SOCIALACCOUNT_AUTO_SIGNUP = True
  </code></pre>