Show in-app notification when an update is availble

Change-Id: Ia27addc67f70adf654846ef1a0d2bf9bd9d8024f
diff --git a/sw.js b/sw.js
index 53519f3..403b19e 100644
--- a/sw.js
+++ b/sw.js
@@ -1,4 +1,4 @@
-// Version: 1.0.3
+// Version: 1.0.4
 var CACHE_NAME = 'all-v1';
 var urlsToCache = [
   '/',