couple of things did you do this for cedar you need to explicitly say this (I am sure you have done this but here for completeness)
heroku create --stack cedar
ensure that your package.json is at the root
heroku have a good article on this
You should now be able to
git push heroku master
Have you added Procfile and package.json to your local git repo. and committed them?
I had created them but forgot to add & commit them so when pushed these files weren't uploaded hence Heroku didn't know the type of app.
Adding, committing & re-pushing fixed this.
Obvious when you know:-)