LT-107: Add countdown dialog

- Remove ui from meteor-stale-session package

Packages/lesiontracker/client/components/timeoutCountdownDialog/timeoutCountdownDialog.js

@@ -0,0 +1,9 @@
+
+Template.timeoutCountdownDialog.helpers({
+    leftTime: function(e) {
+        return Session.get("countdownDialogLeftTime");
+    },
+    secondsText: function() {
+        return Session.get("countdownDialogLeftTime") > 1? "seconds": "second";
+    }
+});