Fix version display in the HTML title (#249)

Forgot to remove the tags when including the version number in the HTML
title. Use the `striptags` filter to fix this in the base template.

doc/_templates/layout.html

@@ -21,6 +21,6 @@
  {% if title == '' or title == 'Home' %}
  <title>{{ docstitle|striptags|e }}</title>
  {% else %}
- <title>{{ title|striptags|e }}{{ titlesuffix }}</title>
+ <title>{{ title|striptags|e }} | {{ docstitle|striptags|e }}</title>
  {% endif %}
 {% endblock %}