title: How to highlighting differences between 2 html files
body: <p>My web application has job descriptions. These job descriptions can be modified by some users. Each modification result in a new version of the job description.</p>
  
  <p>The content of the job description is edited by the users, in html, directly in the textearea using the tinymce editor.</p>
  
  <p>I want to be able to show a user the modifications made to the content from one version to another.
  The simpler the better, for example, just a green background for added content and a blue background for removed content.</p>
  
  <p>The application is a ruby on rails app and I have full access to my server (slicehost)</p>