Fixed #15667 -- Added template-based widget rendering.

Thanks Carl Meyer and Tim Graham for contributing to the patch.

tests/runtests.py

@@ -169,6 +169,11 @@ def setup(verbosity, test_labels, parallel):
         'The GeoManager class is deprecated.',
         RemovedInDjango20Warning
     )
+    warnings.filterwarnings(
+        'ignore',
+        'django.forms.extras is deprecated.',
+        RemovedInDjango20Warning
+    )
 
     # Load all the ALWAYS_INSTALLED_APPS.
     django.setup()