title: Recording classes in Django Admin with @admin.register decorator
body: <p>I am testing the new <code>@admin.register</code> decorator that is a new feature from Django 1.7.
  I am currently using Django 1.8.2 and Python 3 and happened me the following situation in relation to <code>@admin.register</code> decorator:</p>
  
  <p>In my <code>admin.py</code> file I have:</p>
  
  <pre><code>from django.contrib import admin
  from .models import Track
  
  # Register your models here.
  @admin.register(Track)
  class TrackAdmin(admin.ModelAdmin):
      list_display = ('title','artist')
  </code></pre>
  
  <p>And when I try <code>http://localhost:8000/admin/</code> I get the following output in my browser:</p>
  
  <p><img src="https://i.stack.imgur.com/aOQbr.png" alt="AttributeError"></p>
  
  <p>Now, When I use the <code>admin.site.register(Track,TrackAdmin)</code>that is the traditional way of register models and classes in the django admin, happened me the same</p>
  
  <pre><code>from django.contrib import admin
  from .models import Track
  
  
  # Register your models here.
  
  class TrackAdmin(admin.ModelAdmin):
      list_display = ('title','artist')
  
  admin.site.register(Track,TrackAdmin)
  </code></pre>
  
  <p>How to can I use the @admin.register decorator for record together classes? <code>(Track and TrackAdmin)</code></p>
  
  <p>Thanks a lot. :)</p>