add score task to schedule and remove highlights task

config/schedule.rb

@@ -19,6 +19,7 @@
 
 # Learn more: http://github.com/javan/whenever
 
-every 5.minutes do
-  rake 'mainPage:highlights'
+# update score of learning objects
+every 6.hours do
+  rake 'score:leaning_object'
 end