User-agent must contain (gzip).

http://stackoverflow.com/questions/7140035/http-server-not-honoring-accept-encoding-gzip-unless-user-agent-is-known-browse

Reviewed in https://codereview.appspot.com/8288046/.
diff --git a/tests/test_json_model.py b/tests/test_json_model.py
index d461e4c..96570f6 100644
--- a/tests/test_json_model.py
+++ b/tests/test_json_model.py
@@ -140,7 +140,8 @@
         headers, path_params, query_params, body)
 
     self.assertEqual(headers['user-agent'],
-        'my-test-app/1.23.4 google-api-python-client/' + __version__)
+        'my-test-app/1.23.4 google-api-python-client/' + __version__ +
+        ' (gzip)')
 
   def test_bad_response(self):
     model = JsonModel(data_wrapper=False)