How to use multiple heroku accounts, branches, fork heroku apps,
$ heroku git:remote -a app-name
Sets git remote heroku to https://git.heroku.com/app-name.git
$ git remote rename heroku heroku-staging
$ heroku plugins:install heroku-accounts
$ heroku accounts:add personal
Enter your Heroku credentials.
Email: david@heroku.com
Password: ******
$ heroku accounts
$ heroku accounts:set personal
$ heroku config -s -a existing-heroku-app > config.txt
$ cat config.txt | tr '\n' ' ' | xargs heroku config:set -a new-heroku-app
$ heroku plugins:install heroku-fork