App works fine locally, but crashes on deploy to Heroku


Just finished migrating Michael H.'s sample app to rails 4 and ruby
Everything works great locally, but when i deploy to heroku the app
crashes and the logs don’t give me anything.

the app:

the error message in the browser:

An error occurred in the application and your page could not be served.
Please try again in a few moments.

If you are the application owner, check your logs for details.

Heroku logs:

2013-05-20T22:13:22.838866+00:00 heroku[web.1]: Process exited with
status 0
2013-05-20T22:13:22.853999+00:00 heroku[web.1]: State changed from
starting to crashed