Centre the sponsor line in the footer, cache-bust the stylesheet

scripts/sync_posts.py

@@ -248,6 +248,7 @@ POST_PAGE = """<!DOCTYPE html>
       <a href="mailto:oliver@oc-guy.com">Email</a>
     </nav>
   </div>
+  <p class="sponsor-foot">Our Sponsor: <a href="https://ODOO4projects.com/?utm_source=oc-guy.com&amp;utm_medium=website&amp;utm_campaign={sponsor_campaign}" target="_blank" rel="noopener sponsored">Awesome Odoo Community Hosting</a></p>
 </footer>
 </body>
 </html>