CLASSROOMIO-T-10: Add basic google analytics

src/template.html

@@ -13,6 +13,16 @@
 	<link rel="icon" type="image/png" href="favicon.ico">
 	<link rel="icon" type="image/png" sizes="32x32" href="/logo-32.png">
 
+	<!-- Global site tag (gtag.js) - Google Analytics -->
+	<script async src="https://www.googletagmanager.com/gtag/js?id=G-C7WBN0S06R"></script>
+	<script>
+		window.dataLayer = window.dataLayer || [];
+		function gtag() { dataLayer.push(arguments); }
+		gtag('js', new Date());
+
+		gtag('config', 'G-C7WBN0S06R');
+	</script>
+
 	<!-- Sapper creates a <script> tag containing `src/client.js`
 	     and anything else it needs to hydrate the app and
 	     initialise the router -->