[CLEANUP] Use single quotes for strings in the gemspec file

Closes #12

page_title_helper.gemspec

@@ -1,20 +1,20 @@
 # -*- encoding: utf-8 -*-
-$:.push File.expand_path("../lib", __FILE__)
-require "page_title_helper/version"
+$:.push File.expand_path('../lib', __FILE__)
+require 'page_title_helper/version'
 
 Gem::Specification.new do |s|
-  s.name        = "page_title_helper"
+  s.name        = 'page_title_helper'
   s.version     = PageTitleHelper::VERSION
   s.platform    = Gem::Platform::RUBY
-  s.summary     = "Simple, internationalized and DRY page titles and headings for Rails."
-  s.description = "Simple, internationalized and DRY page titles and headings for rails."
+  s.summary     = 'Simple, internationalized and DRY page titles and headings for Rails.'
+  s.description = 'Simple, internationalized and DRY page titles and headings for Rails.'
 
-  s.required_ruby_version     = ">= 1.9.3"
-  s.required_rubygems_version = ">= 1.3.6"
+  s.required_ruby_version     = '>= 1.9.3'
+  s.required_rubygems_version = '>= 1.3.6'
 
-  s.authors  = ["Lukas Westermann"]
-  s.email    = ["lukas.westermann@gmail.com"]
-  s.homepage = "http://github.com/lwe/page_title_helper"
+  s.authors  = ['Lukas Westermann']
+  s.email    = ['lukas.westermann@gmail.com']
+  s.homepage = 'http://github.com/lwe/page_title_helper'
 
   s.files            = `git ls-files`.split("\n")
   s.test_files       = `git ls-files -- {test,spec,features}/*`.split("\n")