Use SimpleCov directly so that coverage can be inspected locally

Gemfile

@@ -7,5 +7,6 @@ group :development do
   gem 'cucumber', '~> 2.1'
   gem 'test-unit', '~> 3.1'
 
+  gem 'simplecov', :require => false
   gem 'coveralls', :require => false
 end

features/support/env.rb

@@ -1,7 +1,11 @@
-if ENV['CI']
-  require 'coveralls'
-  Coveralls.wear!
-end
+require 'simplecov'
+require 'coveralls'
+
+formatters = [SimpleCov::Formatter::HTMLFormatter]
+formatters << Coveralls::SimpleCov::Formatter if ENV['CI']
+
+SimpleCov.formatters = formatters
+SimpleCov.start
 
 require 'test/unit/assertions'
 require 'jekyll-responsive-image'