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* renamed ``Dependency.async`` to ``Dependency.async_``.
Fix for `16 <https://github.com/lehins/django-smartfields/issues/16>`_.
Thanks `zglennie <https://github.com/zglennie>`_
* Fix compatibility with ``Django=2.x``:
* Added ``app_name='smartifelds'`` to ``urls.py`` file
* Stop using ``_size`` and ``_set_size()`` attributes in ``NamedTemporaryFile``,
since those where only available in ``Django=1.x``