Django-mama-cas

* Add support for CAS 3.0 features
* Allow multiple custom attribute callbacks
* Use gevent for asynchronous single sign-out requests, if available
* Fix error when a malformed username was provided
* Fix logout occurring for a renew request
* Fix redirects not checking for a valid URL
* Improve removal of invalid tickets
* Default ``MAMA_CAS_FOLLOW_LOGOUT_URL`` to ``True``
* Deprecate ``MAMA_CAS_USER_ATTRIBUTES`` and ``MAMA_CAS_PROFILE_ATTRIBUTES``

.. warning::

The ``MAMA_CAS_ATTRIBUTES_CALLBACK`` setting was renamed to
``MAMA_CAS_ATTRIBUTE_CALLBACKS`` and now takes a tuple of dotted
paths to callables.

* Fix validation response not returning PGTIOU

* Add single sign-out functionality
* Add callback for returning custom user attributes
* Fix support for custom user models with no ``username`` field

* Fix Python 2.6 compatibility

* Generate CAS 2.0 XML responses instead of using templates
* Expire PGTs according to SESSION_COOKIE_AGE
* Change ticket created field to expiry date
* Change ticket expiration duration to seconds
* Fix ticket cleanup cascading to valid tickets

.. warning::

The ``created`` field on ``ServiceTicket``, ``ProxyTicket`` and
``ProxyGrantingTicket`` was renamed to ``expires``. If upgrading,
you must ensure this field is renamed accordingly.

.. warning::

The ``MAMA_CAS_TICKET_EXPIRE`` setting previously specified ticket
expiration in minutes and defaulted to *5*. Now the setting is
specified in seconds and defaults to *90*.

* Django 1.6 compatibility
* Handle exceptions raised by authentication backends