Unable to `git push heroku master` until I add an SSH key

[sumbach]

I ran through these instructions on my new MacBook, and git push heroku master failed until I added my new SSH public key to my Heroku account.

If it's possible to push to Heroku via HTTPS or there's some other way to avoid SSH key setup, that would be ideal.

Otherwise, we probably need to add some additional instructions to create and SSH key and add to Heroku. On the upside, the incremental effort to create and configure a GitHub account will be less.