[DO NOT MERGE] Update Security String to 2017-04-01 on lmp-dev am: ffab69998a  -s ours am: 0f30aa9801 am: 05ebddebe5  -s ours am: 101c043b17 am: 58086ff4aa
am: fec9d76740

Change-Id: I70bd052bfddbd2cd926bc547a54d4831d63831f1