Bump Security String to 2019-04-05

Implemented:
============
CVE:            References:  Type:  Severity:  Updated AOSP versions:
CVE-2019-2027   A-119120561  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2028   A-120644655  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2029   A-120612744  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2031   A-120502559  EoP    High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2034   A-122035770  EoP    High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2035   A-122320256  EoP    High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2037   A-119870451  ID     High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2038   A-121259048  ID     High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2039   A-121260197  ID     High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9

Not Implemented:
================
None

Not Applicable (platform source):
===============
CVE:            References:  Type:  Severity:  Updated AOSP versions:
CVE-2019-2026   A-120866126  EoP    High       8.0
CVE-2019-2030   A-119496789  EoP    High       9
CVE-2019-2032   A-121145627  EoP    High       8.0, 8.1, 9
CVE-2019-2033   A-121327565  EoP    High       9
CVE-2019-2040   A-122316913  ID     High       9
CVE-2019-2041   A-122034690  EoP    High       8.1, 9 (device-specific)

Change-Id: I72ca6a2040a842ea967ad24e2fa605f095bbf4eb