Change single quotes to double quotes

spec/rails_helper.rb

@@ -1,16 +1,16 @@
-ENV['RAILS_ENV'] ||= 'test'
-if ENV['TRAVIS']
-  require 'coveralls'
-  Coveralls.wear!('rails')
+ENV["RAILS_ENV"] ||= "test"
+if ENV["TRAVIS"]
+  require "coveralls"
+  Coveralls.wear!("rails")
 end
-require File.expand_path('../../config/environment', __FILE__)
+require File.expand_path("../../config/environment", __FILE__)
 abort("The Rails environment is running in production mode!") if Rails.env.production?
 
-require 'rspec/rails'
-require 'spec_helper'
-require 'capybara/rails'
-require 'capybara/rspec'
-require 'selenium/webdriver'
+require "rspec/rails"
+require "spec_helper"
+require "capybara/rails"
+require "capybara/rspec"
+require "selenium/webdriver"
 
 Rails.application.load_tasks if Rake::Task.tasks.empty?
 I18n.default_locale = :en