title: lazy reference: doesn't provide model user?
body: <p>Currently I'm using Django 1.11 and Python 3.6.  I'm attempting to create a custom user model with a new application that authenticates with LDAP, but i'm greeted with the following error message.</p>
  
  <pre><code>    raise ValueError("\n".join(error.msg for error in errors))
  ValueError: The field admin.LogEntry.user was declared with a lazy reference to 'accounts.user', but app 'accounts' doesn't provide model 'user'.
  </code></pre>
  
  <p>Settings.py Installed Apps, Auth Backends, and Auth_User Model:</p>
  
  <pre><code>INSTALLED_APPS = [
      'django_python3_ldap',
      'django_extensions',
      'django_filters',
      'django.contrib.admin',
      'django.contrib.auth',
      'django.contrib.contenttypes',
      'django.contrib.sessions',
      'django.contrib.messages',
      'django.contrib.staticfiles',
      'accounts',
  ]
  
  
  AUTHENTICATION_BACKENDS = (
      'django_python3_ldap.auth.LDAPBackend',
      'django.contrib.auth.backends.ModelBackend',
  )
  
  AUTH_USER_MODEL = "accounts.User"
  </code></pre>
  
  <p>Admin.py:</p>
  
  <pre><code>from django.contrib import admin
  from django.conf import settings
  from .models import User
  
  # Register your models here.
  admin.site.register(User)
  </code></pre>
  
  <p>Below is my models.py:</p>
  
  <pre><code>from __future__ import unicode_literals
  from django.utils import timezone
  from django.contrib.auth.models import (AbstractBaseUser,PermissionsMixin)
  from django.db import models
  from django.forms import ModelForm
  
  
  class User(AbstractBaseUser, PermissionsMixin):
      email = models.EmailField(unique=True)
      username = models.CharField(max_length=25, unique=True)
      first_name = models.CharField(max_length=40)
      last_name = models.CharField(max_length=140)
      date_joined = models.DateTimeField(default=timezone.now)
      is_active = models.BooleanField(default=True)
      is_staff = models.BooleanField(default=False)
      facility = models.CharField(max_length=140)
      jobdescription = models.CharField(max_length=140)
      positiondescription = models.CharField(max_length=140)
  
      USERNAME_FIELD = "username"
  </code></pre>