title: How to force a record to save itself even if I have not changed any attributes
body: <p>In order to clean up some bad data I added a before save callback. Now I need to force all the models to be saved again. However no update operation happens if I do this</p>
  
  <pre><code>User.first.save
  </code></pre>
  
  <p>How do I force all the models to perform save operation even though I don't have any attributes changed.</p>