Bump Security Patch Level to 2018-05-01

Implemented Patches
===================
CVE-2017-13313  A-74114680      High        Change 214967
CVE-2017-13319  A-71868329      High        Change 214969
CVE-2017-13323  A-73826242      Moderate    Change 214970
CVE-2017-13322  A-67862398      Moderate    Change 214972

Skipped Patches
===============
CVE-2017-13310  A-71992105      High        No ViewPager
CVE-2017-13320  A-72764648      High        No libmpeg2
CVE-2017-13315  A-70721937      High        No DcParamObject.java
CVE-2017-13316  A-73311729      Moderate    Not applicable

Reference Version: 6.0

Change-Id: If80c7cebf54850485975fc9bb981b1f1ad6166d2