app.del deprecated

[artzstudio]

Hey there, just flagging this for you that Express 4 deprecated app.del in favor of app.delete.
Just gives me an annoying warning message, otherwise still works.

express: app.del: Use app.delete instead

I'd submit a pull request but figured you probably want to maintain compatibility. Thoughts?

[windwaterbo]

With express < 4

app.del(function(req, res, next) {
  next(new Error('not implemented'));
})

With express 4

app.delete(function(req, res, next) {
  next(new Error('not implemented'));
})

See http://expressjs.com/4x/api.html#router.route for the method