title: Access django-custom-user manager method in migration
body: <p>I'd like to seed a superuser record in a data migration for a django 1.7 project. I'm using the <a href="https://github.com/jcugat/django-custom-user" rel="noreferrer">django-custom-user</a> app. My migration looks like this:</p>
  
  <pre><code># -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  from django.db import models, migrations
  
  def load_data(apps, schema_editor):
      EmailUser = apps.get_model('custom_user', 'EmailUser')
      root = EmailUser.objects.create_superuser(email='admin@somesite.com', password='supersecure')
  
  
  class Migration(migrations.Migration):
      dependencies = [
          ('accounts', '0001_initial'),
      ]
  
      operations = [
          migrations.RunPython(load_data)
      ]
  </code></pre>
  
  <p>When running <code>./manage.py migrate</code> I get the following error:</p>
  
  <pre><code>Running migrations:
    Applying accounts.0002_initial_data...Traceback (most recent call last):
    File "./manage.py", line 10, in &lt;module&gt;
      execute_from_command_line(sys.argv)
    File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
      utility.execute()
    File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
      self.fetch_command(subcommand).run_from_argv(self.argv)
    File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
      self.execute(*args, **options.__dict__)
    File "/usr/local/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
      output = self.handle(*args, **options)
    File "/usr/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 161, in handle
      executor.migrate(targets, plan, fake=options.get("fake", False))
    File "/usr/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 68, in migrate
      self.apply_migration(migration, fake=fake)
    File "/usr/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 102, in apply_migration
      migration.apply(project_state, schema_editor)
    File "/usr/local/lib/python2.7/site-packages/django/db/migrations/migration.py", line 105, in apply
      operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
    File "/usr/local/lib/python2.7/site-packages/django/db/migrations/operations/special.py", line 117, in database_forwards
      self.code(from_state.render(), schema_editor)
    File "/Users/spoolphiz/work/somesite/accounts/migrations/0002_initial_data.py", line 14, in load_data
      root = EmailUser.objects.create_superuser(email='admin@somesite.com', password='f00b@r')
  AttributeError: 'Manager' object has no attribute 'create_superuser'
  </code></pre>
  
  <p>I see that <code>EmailUserManager</code> <a href="https://github.com/jcugat/django-custom-user/blob/master/custom_user/models.py#L50" rel="noreferrer">does have a create_superuser method</a>. Am I incorrectly invoking the manager's function?</p>
  
  <p>Edit:</p>
  
  <p>I see the <a href="https://stackoverflow.com/questions/3291556/how-do-i-access-auth-users-user-objects-create-user-in-a-south-migration">same issue here</a>. Is duplicating all code really the best solution? Seems like at that point I'd be better off using RunSQL and manually performing the inserts. </p>