title: Reserved word issue with ActiveAdmin rails 3.2
body: <p>I have made the following addition to my active admin interface:</p>
  
  <pre><code>action_item :only =&gt; :show do
     link_to('Approve this article', approve_admin_article_path(article)) if article.approved.nil?
  end
  
  member_action :approve, :method =&gt; :get do
    # do approval
    redirect_to :action =&gt; :show, :notice =&gt; "Approved!"
  end
  </code></pre>
  
  <p>This throws the following error: </p>
  
  <p>undefined method `approved' for               
  :Arbre::HTML::Article</p>
  
  <p>What I think is happening is Active Admin thinks I'm passing an article tag in, not an article class?</p>
  
  <p>Does anyone know of a work around for this? perhaps aliasing?</p>
  
  <p>Thanks!</p>
  
  <p>class Article &lt; ActiveRecord::Base</p>
  
  <p>attr_accessible :body</p>
  
  <p># Relations:
    belongs_to :articleable, polymorphic: true, :counter_cache => true
    has_many :comments, as: :commentable, order: 'created_at DESC', dependent: :destroy</p>
  
  <p># Validations
    validates_presence_of :body
    validates_length_of :body, maximum: 15000</p>
  
  <p>end</p>