Add proxy model test that fails in Django 1.5
Fix Django 1.5 support, tests pass again.

The reason polymorphic broke was because it couldn't find some managers
anymore in the inheritance tree. Django 1.5 removes these and replaces
them with an `AbstractManagerDescriptor`. This patch restores those objects
Fix passing custom querysets to related managers.

* The custom manager was not assigned to _default_manager;
  get_first_user_defined_manager() always returned None
* The PolymorphicManager couldn't remember it's custom queryset;
  a RelatedManager creates a new instance of a manager, so the queryset
  parameter should be known at class-level, not object level.
* The old method of providing a custom queryset class has been deprecated.
Made Diederik a core developer! Thanks a lot for your work!

(Core developers have master commit rights)
Merge pull request #31 from vdboor/django15

Fix Django 1.5 (proxy models broke polymorphism)
Merge pull request #33 from vdboor/fix_related_queryset

Fix related queryset (please merge before #32)
Support proxy models (still requires one query per proxied model, not optimal)
Update for proxy models and Django 1.5

Only monkeypatch when using Django < 1.5
Updated test
Optimization - don't do extra queries for proxy models
Fix base_manager unit test

As more methods are added to the PolymorphicModel, the attr dict changes
ordering in the meta class. By making the ordering of managers
consistent, this problem no longer occurs.
Rename variables in polymorphic/query.py for clarity

(split from previous commit by @jedediah)
Handle non-distinct results from base object query
Fixes proxy models in the admin

The PolymorphicParentModelAdmin was getting the concrete model ids for
the add form.
Updated proxy model tests

Extracted classes from original proxy test.
Added another simple proxy model test.
Moved the test case to a seemingly better spot.
Included Proxy models in example app.
Optimize transmogrify() function, assign __class__ instead.
Merge branch 'proxy_models_15' - add proxy model support!