title: bundle exec rspec spec/requests/static_pages_spec.rb from Hartl's tutorial isn't working
body: <p>I'm following Michael Hartl's ruby on rails tutorial to test the sample app(3.2.1 Test-driven development), but I'm getting following error after typing <code>bundle exec rspec spec/requests/static_pages_spec.rb</code> </p>
  
  <pre><code>/home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium/webdriver/common/zipper.rb:1:in `require': cannot load such file -- zip/zip (LoadError)
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium/webdriver/common/zipper.rb:1:in `&lt;top (required)&gt;'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium/webdriver/common.rb:9:in `require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium/webdriver/common.rb:9:in `&lt;top (required)&gt;'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium/webdriver.rb:29:in `require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium/webdriver.rb:29:in `&lt;top (required)&gt;'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium-webdriver.rb:1:in `require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/selenium-webdriver-2.0.0/lib/selenium-webdriver.rb:1:in `&lt;top (required)&gt;'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `block (2 levels) in require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `each'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `block in require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `each'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `require'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler.rb:132:in `require'
      from /home/rahul/Downloads/rails_projects/sample_app/config/application.rb:12:in `&lt;top (required)&gt;'
      from /home/rahul/Downloads/rails_projects/sample_app/config/environment.rb:2:in `require'
      from /home/rahul/Downloads/rails_projects/sample_app/config/environment.rb:2:in `&lt;top (required)&gt;'
      from /home/rahul/Downloads/rails_projects/sample_app/spec/spec_helper.rb:3:in `require'
      from /home/rahul/Downloads/rails_projects/sample_app/spec/spec_helper.rb:3:in `&lt;top (required)&gt;'
      from /home/rahul/Downloads/rails_projects/sample_app/spec/requests/static_pages_spec.rb:1:in `require'
      from /home/rahul/Downloads/rails_projects/sample_app/spec/requests/static_pages_spec.rb:1:in `&lt;top (required)&gt;'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `load'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `block in load_spec_files'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `each'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `load_spec_files'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/command_line.rb:22:in `run'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/runner.rb:80:in `run'
      from /home/rahul/.rvm/gems/ruby-2.0.0-p247@railstutorial_rails_4_0/gems/rspec-core-2.13.1/lib/rspec/core/runner.rb:17:in `block in autorun'
  </code></pre>
  
  <p>Here is the code from <code>spec/requests/static_pages_spec</code> file:</p>
  
  <pre><code>require 'spec_helper'
  
  describe "Static pages" do
  
    describe "Home page" do
  
      it "should have the content 'Sample App' " do
        visit '/static_pages/home'
        expect(page).to have_content('Sample App')
      end
  
    end
  
  end
  </code></pre>
  
  <p><code>Gemfile</code>:</p>
  
  <pre><code>source 'https://rubygems.org'
  ruby '2.0.0'
  #ruby-gemset=railstutorial_rails_4_0
  
  gem 'rails', '4.0.0'
  
  group :development, :test do
    gem 'sqlite3', '1.3.7'
    gem 'rspec-rails', '2.13.1'
  end
  
  group :test do
    gem 'selenium-webdriver', '2.0.0'
    gem 'capybara', '2.1.0'
  end
  
  gem 'sass-rails', '4.0.0'
  gem 'uglifier', '2.1.1'
  gem 'coffee-rails', '4.0.0'
  gem 'jquery-rails', '2.2.1'
  gem 'turbolinks', '1.1.1'
  gem 'jbuilder', '1.0.2'
  
  group :doc do
    gem 'sdoc', '0.3.20', require: false
  end
  
  group :production do
    gem 'pg', '0.15.1'
    gem 'rails_12factor', '0.0.2'
  end
  </code></pre>
  
  <p><code>routes.rb</code>:</p>
  
  <pre><code>SampleApp::Application.routes.draw do
    get "static_pages/home"
    get "static_pages/help"
  end
  </code></pre>
  
  <p><strong>OS</strong>: Ubuntu 13.04</p>
  
  <p>I've been searching for solution, but have not found one. Please keep in mind that I'm new to Ruby on Rails and web development.</p>