title: Activerecord Group by ENUM
body: <p>I'm using rails 4.1 and the new enum functionality to include an array of enums in my model class e.g:</p>
  
  <pre><code>class Campaign &lt; ActiveRecord::Base    
    enum status: [:pending, :active, :paused, :complete]
  
  end
  </code></pre>
  
  <p>I want to query campaigns and list a count by status e.g:</p>
  
  <pre><code>Campaign.all.group("status").count
  </code></pre>
  
  <p>This simple query works fine however returns the integer value of the enum from the DB.  Is there an easy rails way to convert this to the string representation?</p>