App is prepared for Heroku's Cedar stack.
Try using latest version of newrelic_rpm on Heroku.
Try using thin rather than unicorn on Heroku.
Use unicorn.
Test without New Relic.
It's not New Relic RPM.
It appears that Sinatra > 1.3.3 breaks things at the moment.
Merge branch 'cedar'
Updated README to include correct references to herokuapp.com rather than heroku.com after migrating all apps to Cedar. Finally closes #23.