Fixed #24429 -- Doc'ed that Django 1.8 doesn't require an integer PK for custom user models.

Django expects your custom User model to meet some minimum requirements.

1. Your model must have an integer primary key.

2. Your model must have a single unique field that can be used for

#. Your model must have a single unique field that can be used for

   identification purposes. This can be a username, an email address,

   or any other unique attribute.

3. Your model must provide a way to address the user in a "short" and

#. Your model must provide a way to address the user in a "short" and

   "long" form. The most common interpretation of this would be to use

   the user's given name as the "short" identifier, and the user's full

   name as the "long" identifier. However, there are no constraints on

   what these two methods return - if you want, they can return exactly

   the same value.

.. versionchanged:: 1.8

    Older versions of Django required your model to have an integer primary

    key as well.

The easiest way to construct a compliant custom User model is to inherit from

:class:`~django.contrib.auth.models.AbstractBaseUser`.

:class:`~django.contrib.auth.models.AbstractBaseUser` provides the core