Move DDF requirement to 'test' extra in setup.py

Try and avoid failures in downstream projects caused by DDF being
unavailable except from IC's own DevPy, by making it possible to install
ICEkit Events without DDF unless you explicitly ask for the 'test'
extras.

setup.py

@@ -49,10 +49,6 @@
     include_package_data=True,
     install_requires=[
         'Django<1.9',
-        # TODO Specific version of django-dynamic-fixture is necessary to avoid
-        # AttributeError: can't set attribute` failures on polymorphic models.
-        # See https://github.com/paulocheque/django-dynamic-fixture/pull/59
-        'django-dynamic-fixture==1.9.0+0.caeb3427399edd3b0d589516993c7da55e0de560.ixc',
         'django-icekit',
         'django-polymorphic',
         'django-polymorphic-tree',
@@ -67,7 +63,13 @@
         'dev': ['ipdb', 'ipython'],
         'fluentevent': ['django-fluent-contents'],
         'postgres': ['psycopg2'],
-        'test': ['coverage', 'django-nose', 'nose-progressive', 'django-webtest', 'WebTest']
+        'test': [
+            'coverage', 'django-nose', 'nose-progressive', 'django-webtest', 'WebTest',
+            # TODO Specific version of django-dynamic-fixture is necessary to avoid
+            # AttributeError: can't set attribute` failures on polymorphic models.
+            # See https://github.com/paulocheque/django-dynamic-fixture/pull/59
+            'django-dynamic-fixture==1.9.0+0.caeb3427399edd3b0d589516993c7da55e0de560.ixc',
+        ]
     },
     setup_requires=['setuptools_scm'],
 )