Upgrade to Cedar 14 on Heroku

Use with caution, this does not test to be sure your app will work with the new stack:

$ heroku stack:set cedar-14
$ git commit --allow-empty -m "Upgrading to Cedar-14"
$ git push heroku master

You can rollback with:

$ heroku releases
$ heroku rollback [previous release]
$ heroku stack:set cedar

[previous release] is a release number like v12 taken from the output of the heroic releases command.

From: https://devcenter.heroku.com/articles/cedar-14-migration