Restrict wheel to py27 only

Refs GH-2330

setup.cfg

@@ -8,5 +8,5 @@ ignore = F999,E501,E128,E124,E402,W503,E731,C901
 max-line-length = 100
 exclude = .tox,.git,*/migrations/*,node_modules/*,src/sentry/static/sentry/vendor/*,docs/*
 
-[wheel]
-universal = 1
+[bdist_wheel]
+python-tag = py27