fix noscript mode to not allocate notification ids on each refresh

Now the javascript does an ajax call at the start to request the url
to use to poll, and the notification id is generated then, once we know
javascript is working.

templates/dashboard.hamlet

@@ -0,0 +1,10 @@
+^{content}
+$if warnNoScript
+  <noscript>
+    <div .navbar .navbar-fixed-bottom>
+      <div .navbar-inner>
+        <div .container>
+          Javascript is disabled; cannot update in real-time.
+          <div .btn-group>
+            <a .btn .btn-primary href="@{NoScriptAutoR}">Auto-refresh every 3 seconds #
+            <a .btn .btn-primary href="@{NoScriptR}">Manually refresh

templates/longpolling.julius

@@ -1,9 +1,12 @@
 function longpoll_#{ident}() {
-	longpoll('@{gethtml}', '#{ident}'
+	longpoll(longpoll_#{ident}_url, '#{ident}'
 		, function() { setTimeout(longpoll_#{ident}, #{delay}); }
 		, function() { webapp_disconnected(); }
 	);
 }
 $(function() {
-	setTimeout(longpoll_#{ident}, #{startdelay});
+	$.get("@{geturl}", function(url){
+		longpoll_#{ident}_url = url;
+		setTimeout(longpoll_#{ident}, #{startdelay});
+	});
 });