title: Rails tire:import with custom logic
body: <p>I have a Ruby on rails 3.2 application where I'm trying to use Tire and Elastic Search.</p>
  
  <p>I have a User model that has the following declarations:</p>
  
  <pre><code>include Tire::Model::Search
  include Tire::Model::Callbacks
  </code></pre>
  
  <p>I then carried out an initial import of records into Elastic Search by calling:</p>
  
  <pre><code>rake environment tire:import CLASS=User FORCE=true
  </code></pre>
  
  <p>Is it possible to customise the import task, such that it skips one user? I have a system user that I would prefer not to be indexed?</p>