Fixes issue #85. Also moves all json imports to go through oauth2client.anyjson.  Reviewed in http://codereview.appspot.com/5531064/.
diff --git a/Makefile b/Makefile
index 8d5b402..4f568a4 100644
--- a/Makefile
+++ b/Makefile
@@ -17,6 +17,7 @@
 	python runtests.py tests/test_oauth2client.py
 	python runtests.py tests/test_oauth.py
 	python runtests.py tests/test_protobuf_model.py
+	python runtests.py tests/test_schema.py
 	python runtests.py tests/test_oauth2client_appengine.py
 
 .PHONY: docs