taskcontroller.cfg should be checked before task tracker comes up

Right now, task-controller.cfg should have two mandatory parameters mapreduce.cluster.local.dir and hadoop.log.dir, without which cluster comes up including Task tracker , but when any jobs are submitted, it gives errors.

This will highly confuse the Ops and end-user.

Even though, when every job is submitted, task-controller.cfg is checked, it should be checked in the very beginning when Task tracker comes up.

Expected behaviour is :
1) TT should not come up.
2) TT logs should show why its not come up like which parameter is missing and if found, if the values mismatches with the mapred-site.xml