Update Security String to 2016-04-02 in preparation for April 2016 Security OTA v2 - kernel updates with patches for CVE-2015-1805 am: 2b71be5 am: df28b90 am: b90d094
am: fa24625

* commit 'fa2462551694090da0d0c941d805165c2e2f6dc2':
  Update Security String to 2016-04-02 in preparation for April 2016 Security OTA v2 - kernel updates with patches for CVE-2015-1805