Ruby on Rails app working on c9.io, crashing on Heroku

My Ruby on Rails app works fine in development on cloud9. When I push to Heroku, the application crashes immediately. 'heroku logs' shows:

2015-03-15T17:11:11.909831+00:00 heroku[web.1]: State changed from crashed to starting
2015-03-15T17:11:16.291267+00:00 heroku[web.1]: Starting process with command `bin/rails server -p 42991 -e production`
2015-03-15T17:11:20.262015+00:00 app[web.1]: => Booting Puma
2015-03-15T17:11:20.262090+00:00 app[web.1]: => Rails 4.2.0 application starting in production on http://0.0.0.0:42991
2015-03-15T17:11:20.264853+00:00 app[web.1]: Abort testing: Your Rails environment is running in production mode!
2015-03-15T17:11:20.264972+00:00 app[web.1]: Exiting
2015-03-15T17:11:20.262130+00:00 app[web.1]: => Run `rails server -h` for more startup options
2015-03-15T17:11:20.262170+00:00 app[web.1]: => Ctrl-C to shutdown server
2015-03-15T17:11:21.206693+00:00 heroku[web.1]: State changed from starting to crashed
2015-03-15T17:11:21.193413+00:00 heroku[web.1]: Process exited with status 1
2015-03-15T17:11:22.003251+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=agile-plateau-9101.herokuapp.com request_id=2889a78c-9ccf-4583-ac2b-978683cab62e fwd="149.151.180.124" dyno= connect= service= status=503 bytes=
2015-03-15T17:11:22.536224+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=agile-plateau-9101.herokuapp.com request_id=355eeb91-1fb6-410c-a169-3407d7c2af67 fwd="149.151.180.124" dyno= connect= service= status=503 bytes=

I've tried using unicorn and puma, both with the .rb files Heroku provides, with no luck. I can't even get a console to run on Heroku. 'heroku run rails console' in the IDE shows 'Running rails console attached to terminal... up, run.9870' then brings me back to the IDE console, rather than Heroku's. The Heroku logs for the console command are:

2015-03-15T17:16:48.811613+00:00 heroku[api]: Starting process with command `rails console` by msandford@gmail.com
2015-03-15T17:16:54.386969+00:00 heroku[run.9870]: Awaiting client
2015-03-15T17:16:54.550213+00:00 heroku[run.9870]: Starting process with command `rails console`
2015-03-15T17:16:54.772282+00:00 heroku[run.9870]: State changed from starting to up
2015-03-15T17:17:01.220393+00:00 heroku[run.9870]: State changed from up to complete
2015-03-15T17:17:01.207230+00:00 heroku[run.9870]: Process exited with status 1

Any suggestions on where to begin troubleshooting this?