title: Upgrade ruby to 2.4.0
body: <p>I have upgraded Ruby to version 2.4.0 in my Rails app, but when I try to <code>bundle install</code>, I face with the following error:</p>
  
  <pre><code>An error occurred while installing json (1.8.3), and Bundler cannot continue.
  Make sure that `gem install json -v '1.8.3'` succeeds before  
  </code></pre>