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

* commit 'b90d09439a5901f78e9eae332f163cdc1ff98f49':
  Update Security String to 2016-04-02 in preparation for April 2016 Security OTA v2 - kernel updates with patches for CVE-2015-1805