[PYT-304] Add Google pixel code

Author: Pat Mellon

_templates/layout.html

@@ -12,4 +12,5 @@
   ga('send', 'pageview');
 
 </script>
-{% endblock %}
+<img height="1" width="1" style="border-style:none;" alt="" src="http://www.googleadservices.com/pagead/conversion/795629140/?label=txkmCPmdtosBENSssfsC&amp;guid=ON&amp;script=0"/>
+{% endblock %}