title: Carrierwave juste delete file but doesn't clear database column
body: <p>I use <code>carrierewave</code> to add user avatar in my app </p>
  
  <pre><code>class User &lt; ActiveRecord::Base
    mount_uploader :avatar, AvatarUploader
  end
  </code></pre>
  
  <p>so, when i try to remove avatar with <code>remove_avatar</code> method it just remove the file but not clear database column's value</p>
  
  <p>i have found a discussion about the same subject here : <a href="https://github.com/carrierwaveuploader/carrierwave/issues/401" rel="nofollow">CarrierWave only deletes files, doesn't clear the column or clear the uploader</a> but it seem an old discussion (2 years ago) and maybe carrierewave is updated to fix this issue. any idea please ?</p>