Add optional GA tracking code

app/config/config.yml

@@ -21,6 +21,8 @@ framework:
 twig:
     debug:            %kernel.debug%
     strict_variables: %kernel.debug%
+    globals:
+        google_analytics: %google_analytics%
 
 # Assetic Configuration
 assetic:

app/config/parameters.yml.dist

@@ -13,3 +13,6 @@ parameters:
     locale: en
 
     secret: CHANGE_ME_IN_PROD
+
+    google_analytics:
+        key:

src/Packagist/WebBundle/Resources/views/layout.html.twig

@@ -87,12 +87,15 @@
         <script src="//ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js"></script>
         <script>!window.jQuery && document.write(unescape('%3Cscript src="/js/libs/jquery-1.5.2.min.js"%3E%3C/script%3E'))</script>
         <script src="{{ asset('bundles/packagistweb/js/layout.js') }}"></script>
-        {#<script>
-            var _gaq=[['_setAccount','UA-XXXXX-X'],['_trackPageview']]; // TODO Change UA-XXXXX-X
-            (function(d,t){var g=d.createElement(t),s=d.getElementsByTagName(t)[0];g.async=1;
-            g.src=('https:'==location.protocol?'//ssl':'//www')+'.google-analytics.com/ga.js';
-            s.parentNode.insertBefore(g,s)}(document,'script'));
-        </script>#}
+
+        {% if not app.debug and google_analytics.key %}
+            <script>
+                var _gaq=[['_setAccount','{{ google_analytics.key }}'],['_trackPageview']];
+                (function(d,t){var g=d.createElement(t),s=d.getElementsByTagName(t)[0];g.async=1;
+                g.src=('https:'==location.protocol?'//ssl':'//www')+'.google-analytics.com/ga.js';
+                s.parentNode.insertBefore(g,s)}(document,'script'));
+            </script>
+        {% endif %}
 
         {% block scripts %}{% endblock %}
     </body>