Fix test errors if django is not installed

If django is not installed, then we don't import get_es and then this
code fails. But we don't need the get_es method on QueryTest anyhow,
so this nixes it.

elasticutils/tests/test_django.py

@@ -121,10 +121,6 @@ class ESTest(TestCase):
 
 
 class QueryTest(ElasticTestCase):
-    @classmethod
-    def get_es(cls):
-        return get_es()
-
     @classmethod
     def setup_class(cls):
         super(QueryTest, cls).setup_class()