[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 am: ea0d4b0e54  -s ours am: 45deda3682 am: 235702c0e0
am: 6063089d07

Change-Id: Ide2b5e8584c58e17b9026a9ab5fbb6d3dc2d7e62