WEBSITE-628 add setAllowLinker to GA code

Author: Ed Costello

themes/mongodb/layout.html

@@ -283,6 +283,7 @@
 	var _gaq = _gaq || [];
 	_gaq.push(['_setAccount', 'UA-7301842-8']);
 	_gaq.push(['_setDomainName', 'mongodb.org']);
+	_gaq.push(['_setAllowLinker', true]);
 	{%- if (pagename == "meta/401") or (pagename == "meta/403") or (pagename == "meta/404") or (pagename == "meta/410") %}
 	_gaq.push(['_trackPageview', '/manual/{{pagename}}/?page=' + document.location.pathname + document.location.search + '&from=' + document.referrer]);
 	{%- else %}