For a 404, the stub_app returns application/json when RACK_ENV=test but text/html otherwise. I believe this is a sinatra bug: sinatra/sinatra#500
When using sinatra, error pages include images, and we don't want the schema validator to validate responses for those images.
This makes it easier to test stuff in consuming gems/apps.
This allows all config options to be set in the default_configuration block.
204 means "no content" so there will be no content to validate.
This allows the Endpoint specs to run on their own. They don't have a dependency on Interpol::Configuration.
This will make it consistent with the callback for the ResponseSchemaValidator.
The Test::Unit spec was failing on 1.9 due to: http://travis-ci.org/#!/seomoz/interpol/jobs/1010738.
These generate tests for Test::Unit or RSpec that validate your example data against the JSON scheme of your endpoint.