title: Getting Invalid block tag: 'ckeditor_placeholder' when using ckeditor with Gerbi CMS
body: <p>I am trying to upgrade an install of Gerbi CMS (django-page-cms package name) and I keep receiving the following error. </p>
  
  <p><img src="https://i.stack.imgur.com/TQYtX.png" alt="enter image description here"></p>
  
  <p>Here is the template code (client name removed).</p>
  
  <pre><code>{% extends "base.html" %}
  
  {% load pages_tags markup chunks %}
  
  {% block title %}
      {% if current_page %}
          {% show_content current_page "title" %}
      {% else %}
          &lt;&lt; Client Name &gt;&gt;
      {% endif %}
  {% endblock %}
  
  {% block pagecontent %}
      {% if current_page %}
          {% ckeditor_placeholder "Page Title" with ckeditor %}
          {% ckeditor_placeholder "Page Content" with ckeditor %}
          {% imageplaceholder "Header Image" as header_imgsrc %}
  
          &lt;div class="container"&gt;
              &lt;div class="row-fluid"&gt;
                  &lt;div class="span12"&gt;
                      &lt;hgroup class="heading-section"&gt;
                          &lt;h1&gt;{{ page_title }}&lt;/h1&gt;
                      &lt;/hgroup&gt;
                  &lt;/div&gt;{# /.span12 #}
              &lt;/div&gt;{# /.row #}
              &lt;div class="row-fluid mobile-pad"&gt;
                  &lt;div class="span12"&gt;
                      {{ content|markdown }}
                  &lt;/div&gt;{# /.span12 #}
              &lt;/div&gt;{# /.row l-athletes #}
          &lt;/div&gt;{# /.container #}
      {% endif %}
  {% endblock %}
  </code></pre>
  
  <p>I have followed the ckeditor setup correctly and have the required config stuff in my <em>settings.py</em> file</p>
  
  <pre><code>INSTALLED_APPS = (
      ....
      'ckeditor',
      ....
  )
  
  CKEDITOR_UPLOAD_PATH = "uploads/"
  CKEDITOR_IMAGE_BACKEND = "pillow"
  CKEDITOR_JQUERY_URL = '//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js'
  CKEDITOR_CONFIGS = {
      'default': {
          'width': 600,
          'height': 300,
          'toolbar': 'Full',
      }
  }
  </code></pre>
  
  <p>I have also run <code>collecstatic</code> and <code>syncdb</code> already to try and get the files where they need to be but Gerbi CMS isn't playing nice with ckeditor.</p>
  
  <p>The packages are:</p>
  
  <pre><code>django-page-cms==1.6.2
  django-ckeditor==4.4.7
  </code></pre>
  
  <p>Any thoughts?</p>