[DO NOT MERGE] Update Security String to 2017-04-05 for mnc-dev am: af15999c69 am: f23c50fe08 am: ed7c7adb7e am: 46594018ce  -s ours
am: acc43b9d4d

Change-Id: I7ef4564d7904ae2f6bf3d4d18701fbb9e58a1319