title: Django CMS Plugin using Inline InclusionTag results in Orphaned Plugin
body: <p>I don't know what I am doing wrong as I have followed the documentation. I'm thinking it is some little thing. Here is the scenario:</p>
  
  <p>The plugin is a Text Slideshow plugin. It allows the admin the ability to add text that will cycle like a slideshow.</p>
  
  <p>The models are as follows:</p>
  
  <pre><code>class TextSlideshow(CMSPlugin):
      label = models.CharField(max_length=128)
      interval = models.IntegerField(
          default=5000,
          help_text=_('milliseconds between slides. (1000 equals 1 second)'))
  
      def copy_relations(self, oldinstance):
          for slide in oldinstance.text_slides.all():
              slide.pk = None
              slide.id = None
              slide.text_slide_show = self
              slide.save()
  
      def __unicode__(self):
          return self.label
  
  
  class TextSlide(CMSPlugin):
      text_slide_show = models.ForeignKey(TextSlideshow, related_name="text_slides")
      display_value = models.CharField(max_length=128)
      index = models.IntegerField(verbose_name=_("Display order"))
  </code></pre>
  
  <p>The inline is:</p>
  
  <pre><code>class TextSlideInline(admin.StackedInline):
      model = TextSlide
      fk_name = 'text_slide_show'
  </code></pre>
  
  <p>The plugin is:</p>
  
  <pre><code>class TextSlideshowPlugin(CMSPluginBase):
      model = TextSlideshow
      name = _("Text Slideshow")
      render_template = "text_slideshow.html"
      inlines = [TextSlideInline,]
      module = _("Slideshow")
  
      def __init__(self, model=None, admin_site=None):
          super(TextSlideshowPlugin, self).__init__(model=model,
                                                    admin_site=admin_site)
          for inline in self.inlines:
              inline.placeholder = self.placeholder
              inline.page = self.page
  
      def render(self, context, instance, placeholder):
          slides = instance.text_slides.all().order_by('index')
  
          context.update({
              'model': instance,
              'placeholder': placeholder,
              'slides': slides
          })
          return context
  
  
  plugin_pool.register_plugin(TextSlideshowPlugin)
  </code></pre>
  
  <p>The plugin works and will run flawless, but when the admin user adds text slides like so:</p>
  
  <p><img src="https://i.stack.imgur.com/oxKYJ.png" alt="Text Slideshow Plugin Admin"></p>
  
  <p>When I run <pre><code>./manage.py cms list plugins</code></pre> 
  I get this result:
  <code><pre>==== Plugin report ==== </p>
  
  <p>There are 2 plugin types in your database </p>
  
  <p>ERROR      : not installed </p>
  
  <p>instance(s): 2 </p>
  
  <p>TextSlideshowPlugin 
    model      : cmsslideshow.models.TextSlideshow<br>
    instance(s): 1
  </pre></code></p>
  
  <p>As long as i don't run <pre><code>./manage.py cms delete_orphaned_plugins</code></pre> my slideshow will stay in tact and will work fine.</p>
  
  <p>The text slideshow itself is fine, it's just the inline'd elements which are orphaned.</p>
  
  <p>Please help.</p>