title: LoadError Unable to autoload constant Message
body: <p>In my app; when I submit form, I get this error: </p>
  
  <pre><code>LoadError at /questions
  Unable to autoload constant Message, expected /app/models/message.rb to define it
  </code></pre>
  
  <p>It points to the <code>create</code> action in the <code>Questions</code> controller:</p>
  
  <pre><code>@message = current_user.messages.new(:subject =&gt; "You have a question from #{@question.sender_id}"`
  </code></pre>
  
  <p>Message model:</p>
  
  <pre><code>class Mailboxer::Message &lt; ActiveRecord::Base
    attr_accessible :notification_id, :receiver_id, :conversation_id
  end
  </code></pre>