title: installing nokogiri 1.8.2 (for Metaslpoit)
body: <p>i have a problem with installing nokogiri 1.8.2 
  it shows me this :</p>
  
  <p>An error occurred while installing nokogiri (1.8.2), and Bundler cannot continue.
  Make sure that <code>gem install nokogiri -v '1.8.2'</code> succeeds before bundling.</p>
  
  <p>In Gemfile:
    factory_bot_rails was resolved to 4.8.2, which depends on
      railties was resolved to 4.2.10, which depends on
        actionpack was resolved to 4.2.10, which depends on
          actionview was resolved to 4.2.10, which depends on
            rails-dom-testing was resolved to 1.0.9, which depends on
              nokogiri</p>