Follow Rails conventions for Gemfile quoting

The newly generated Rails application will have single quoted lines in the Gemfile.  We can match that style for consistency in the newly generated application.

templates/Gemfile_additions

@@ -9,25 +9,25 @@ gem 'copycopter_client'
 gem 'airbrake'
 
 group :development do
-  gem "heroku"
+  gem 'heroku'
 end
 
 group :development, :test do
-  gem "rspec-rails", "~> 2.9.0"
-  gem "ruby-debug19"
-  gem "sham_rack"
+  gem 'rspec-rails', '~> 2.9.0'
+  gem 'ruby-debug19'
+  gem 'sham_rack'
 end
 
 group :test do
-  gem "cucumber-rails", "1.3.0"
-  gem "capybara-webkit", "~> 0.11.0"
-  gem "factory_girl_rails"
-  gem "bourne"
-  gem "database_cleaner"
-  gem "timecop"
-  gem "shoulda-matchers"
-  gem "launchy"
-  gem "email_spec"
+  gem 'cucumber-rails', '1.3.0'
+  gem 'capybara-webkit', '~> 0.11.0'
+  gem 'factory_girl_rails'
+  gem 'bourne'
+  gem 'database_cleaner'
+  gem 'timecop'
+  gem 'shoulda-matchers'
+  gem 'launchy'
+  gem 'email_spec'
 end
 
 group :staging, :production do