title: RuntimeError: Model class django.contrib.sites.models.Site doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS
body: <p>I am building an application with Django Rest Framework and AngularJs. I am using Django-rest-auth for my authentication purposes, although, I have not been able to set it up. Anyway, I am trying to set up this <a href="https://github.com/Tivix/angular-django-registration-auth">app</a> with my project. I realized I need to install django-rest-auth-registration to get it running, so I followed this <a href="http://django-rest-auth.readthedocs.org/en/latest/installation.html">documentation</a> to do the following things:</p>
  
  <p>I ran the commands </p>
  
  <blockquote>
    <p>pip install django-rest-auth</p>
  </blockquote>
  
  <p>and</p>
  
  <blockquote>
    <p>pip install django-allauth</p>
  </blockquote>
  
  <p>Any my <strong>settings.py</strong> looks like this:</p>
  
  <pre><code>INSTALLED_APPS = [
      'django.contrib.admin',
      'django.contrib.auth',
      'django.contrib.contenttypes',
      'django.contrib.sessions',
      'django.contrib.messages',
      'django.contrib.staticfiles',
  
      # 3rd party apps
      'rest_framework',
      'rest_framework.authtoken',
      'rest_auth',
      'allauth',
      'allauth.account',
      'rest_auth.registration',
  
      # My app
      'myapp',
  ]
  </code></pre>
  
  <p>I have also added the authentication backends, context_processors, and the proper urls.</p>
  
  <p>However, when I try to migrate, my terminal throws the following error: </p>
  
  <blockquote>
    <p>RuntimeError: Model class django.contrib.sites.models.Site doesn't
    declare an explicit app_label and isn't in an application in
    INSTALLED_APPS.</p>
  </blockquote>
  
  <p>Why do I get this error, and how do I solve it to migrate my project? Thanks!</p>