Renamed AppConfig.setup to ready.

            models_module_name = '%s.%s' % (self.name, MODELS_MODULE_NAME)

            self.models_module = import_module(models_module_name)

    def setup(self):

    def ready(self):

        """

        Override this method in subclasses to run setup code.

        Override this method in subclasses to run code when Django starts.

        """

            self.ready = True

            for app_config in self.get_app_configs():

                app_config.setup()

                app_config.ready()

    def check_ready(self):

        """

    ``model_name``. Raises :exc:`~exceptions.LookupError` if no such model

    exists. ``model_name`` is case-insensitive.

.. method:: AppConfig.setup()

.. method:: AppConfig.ready()

    Subclasses can override this method to perform setup tasks such as

    registering signals. It is called as soon as the registry is fully

    Subclasses can override this method to perform initialization tasks such

    as registering signals. It is called as soon as the registry is fully

    populated.

Application registry

signal internally; it's not generally used in third-party applications.

Since this signal is sent during the app registry population process, and

:meth:`AppConfig.setup() <django.apps.AppConfig.setup>` runs after the app

:meth:`AppConfig.ready() <django.apps.AppConfig.ready>` runs after the app

registry is fully populated, receivers cannot be connected in that method.

One possibility is to connect them ``AppConfig.__init__()`` instead, taking

care not to import models or trigger calls to the app registry.

Improvements thus far include:

* Applications can run code at startup, before Django does anything else, with

  the :meth:`~django.apps.AppConfig.setup` method of their configuration.

  the :meth:`~django.apps.AppConfig.ready` method of their configuration.

* It is possible to omit ``models.py`` entirely if an application doesn't

  have any models.