title: Get type of user modifying record - Rails
body: <p>I have in my model:</p>
  
  <pre><code>attr_accessible :name, as: :admin
  </code></pre>
  
  <p>And in my active admin initializer:</p>
  
  <pre><code>module ActiveAdmin
    class BaseController
      with_role :admin
    end
  end
  </code></pre>
  
  <p>Is it possible to get the role that is editing the record in the model, to do something like this:</p>
  
  <pre><code>validate :thing, if: -&gt;{ modifier == :admin }
  </code></pre>
  
  <p>?</p>