Keep sourcemap when uglyfying JS

Change-Id: I105a209ea500b2d81d6b724489251be5c0876c78
diff --git a/Gruntfile.js b/Gruntfile.js
index f301893..2bd8bb2 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -54,7 +54,12 @@
     requirejs: reqTasks,
     uglify: {
       kalamar : {
-        files: uglyFiles
+        files: uglyFiles,
+        options : {
+          sourceMap: {
+            includeSources: true
+          }
+        }
       }
     },
     imagemin: {