Added some items to the 1.7.1 release notes.

Bugfixes

========

* Replace with actual issue (:ticket:`00000`).

* Added a more helpful error message if you try to migrate an app without first

  creating the ``contenttypes`` table (:ticket:`22411`).

* Modified migrations dependency algorithm to avoid possible infinite recursion.

* Fixed a ``UnicodeDecodeError`` when the ``flush`` error message contained

  Unicode characters (:ticket:`22882`).

  adds a ``get_absolute_url()`` method to any model that appears in

  ``ABSOLUTE_URL_OVERRIDES`` but doesn't define ``get_absolute_url()``.

* Avoided masking some `ImportError` exceptions during application loading

  (:ticket:`22920`).

* Empty ``index_together`` or ``unique_together`` model options no longer

  results in infinite migrations (:ticket:`23452`).