add google analytics support

app/assets/javascripts/ga.js

@@ -0,0 +1,10 @@
+var _gaq = _gaq || [];
+_gaq.push(['_setAccount', 'UA-5243064-17']);
+_gaq.push(['_trackPageview']);
+
+(function() {
+    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
+    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
+    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
+    })();
+

app/views/layouts/application.html.slim

@@ -50,4 +50,5 @@ html
             a  href="https://github.com/wahyd4/Libr/blob/master/README.md" 了解更多信息
 
     = javascript_include_tag 'application'
+    = javascript_include_tag 'ga'
     = yield :javascript_includes