Heroku Doesn't Detect Language

I'm creating a rails app on c9.io.

There is a main dir called rails-tutorial and a sub dir for the actual app called hello_app.

hello_app is a rails app.

when I say git push heroku master. It fails and the reason as I see in the activity logs of heroku is unable to detect language.

My question is: Since git is pushing the whole dir, is heroku not able to find the gemfile in the root to figure out that it is a ruby/rails app?

I've also tried to copy the gemfile to the root dir, that has also not worked.

What am I doing wrong?