Specify the address to listen on (#759)

Currently, this causes the dev server to listen on all addresses by default, which is not the intended behavior, imo.

Author: Scott Olmstead

template/build/dev-server.js

@@ -82,7 +82,7 @@ devMiddleware.waitUntilValid(() => {
   _resolve()
 })
 
-var server = app.listen(port)
+var server = app.listen(port, 'localhost')
 
 module.exports = {
   ready: readyPromise,