title: Usage related_name queryset with Django CMS plugin
body: <p>Python 3</p>
  
  <p>Django 1.9</p>
  
  <p>Django-CMS 3.2.2</p>
  
  <p>I have something like this:</p>
  
  <p>models.py</p>
  
  <pre><code>class PluginModel(CMSPlugin):
      title = models.CharField(max_length=60)
  
  class InlineModel(models.Model):
      title = models.CharField(max_length=60)
      plugin_key = models.ForeignKey('PluginModel' related_name='breakpoints')
  </code></pre>
  
  <p>cms_plugins.py</p>
  
  <pre><code>class InlineModelInline(admin.StackedInline):
      model = InlineModel
  
  class PluginModelPlugin(CMSPluginBase):
      model = PluginModel
      inlines = [InlineModelInline,]
  
      def render(self, context, instance, placeholder):
          context = super(CarouselPlugin, self).render(context, instance, placeholder)
          print(instance.breakpoints.all()) #for simple debug
  </code></pre>
  
  <p>I add a few inlines then save. In edit, all inlines appear normal, but if I publish the page, only an empty list is returned. I understand what it's publication system fault, but how can I make it work?</p>