title: django-easy-pdf displays no content
body: <p>I want to render a pdf file with <strong>Django</strong> using <strong>django-easy-pdf</strong>. I followed <a href="https://django-easy-pdf.readthedocs.io/en/v0.2.0-dev1/usage.html" rel="nofollow noreferrer">these instructions</a>, but I get an empty pdf.</p>
  
  <p>This is my html:</p>
  
  <pre><code>{% extends "easy_pdf/base.html" %}
  
  {% block extra_style %}
  {% endblock %}
  
  &lt;% block content %&gt;
    &lt;div id="summary-block"&gt;
      &lt;p&gt;Here goes that square with data.&lt;/p&gt;
    &lt;/div&gt;
    &lt;div id="declarations-block"&gt;
      &lt;p&gt;Here goes the Main content.&lt;/p&gt;
    &lt;/div&gt;
    &lt;div id="data-block"&gt;
      &lt;p&gt;Here goes all the data from the contract.&lt;/p&gt;
    &lt;/div&gt;
    &lt;div id="clause-block"&gt;
      &lt;p&gt;Here goes the Clause content.&lt;/p&gt;
    &lt;/div&gt;
    &lt;div id="signatures-block"&gt;
      &lt;p&gt;Here goes the signatures content.&lt;/p&gt;
    &lt;/div&gt;
  &lt;% endblock %&gt;
  </code></pre>
  
  <p>And this is my <code>views.py</code>:</p>
  
  <pre><code>from django.shortcuts import render
  from django.conf import settings
  from easy_pdf.views import PDFTemplateView
  
  # Create your views here.
  class ContractPDFView(PDFTemplateView):
      template_name = 'contract.html'
  
      base_url = 'file://' + settings.TEMPLATES_DIR
      download_filename = 'contract.pdf'
  
      def get_context_data(self, **kwargs):
          return super(ContractPDFView, self).get_context_data(pagesize='letter', title='Contract', **kwargs)
  </code></pre>
  
  <p>I don't know what I am missing.</p>