Further fixes to the migration notes for get_query_set

If you are writing a library that needs to call the ``get_queryset`` method and

must support old Django versions, you should write::

    get_queryset = (some_manager.get_queryset

                    if hasattr(some_manager, 'get_queryset')

                    else some_manager.get_query_set)

    get_queryset = (some_manager.get_query_set

                    if hasattr(some_manager, 'get_query_set')

                    else some_manager.get_queryset)

    return get_queryset() # etc

In the general case of a custom manager that both implements its own

``get_queryset`` method and calls that method, and needs to work with older Django

versions, and libraries that have not been updated yet, it is useful to define

a ``get_queryset_compat`` method as below and use it internally to your manager::

    class YourCustomManager(models.Manager):

        def get_queryset(self):

            return YourCustomQuerySet() # for example

        get_query_set = get_queryset

        def active(self): # for example

            return self.get_queryset_compat().filter(active=True)

        def get_queryset_compat(self):

            get_queryset = (self.get_query_set

                            if hasattr(self, 'get_query_set')

                            else self.get_queryset)

            return get_queryset()

This helps to minimize the changes that are needed, but also works correctly in

the case of subclasses (such as ``RelatedManagers`` from Django 1.5) which might

override either ``get_query_set`` or ``get_queryset``.

``shortcut`` view and URLconf

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