use twine for pypi uploads

Makefile

@@ -33,6 +33,7 @@ clean-build:
 	rm -fr .eggs/
 	find . -name '*.egg-info' -exec rm -fr {} +
 	find . -name '*.egg' -exec rm -f {} +
+	find . -name '*.bak' -exec rm -f {} +
 
 clean-pyc:
 	find . -name '*.pyc' -exec rm -f {} +
@@ -72,13 +73,11 @@ docs:
 	$(MAKE) -C docs html
 	$(BROWSER) docs/_build/html/index.html
 
-release: clean
-	python setup.py sdist upload
-	python setup.py bdist_wheel upload
+release: dist
+	twine upload dist/*
 
 dist: clean
 	python setup.py sdist
-	python setup.py bdist_wheel
 	ls -l dist
 
 install: clean