Bump Security String to 2019-05-05

Implemented:
============
CVE:            References:  Type:  Severity:  Updated AOSP versions:
CVE-2019-2043   A-120484087  EoP    Moderate   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2044   A-123701862  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2045   A-117554758  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.1, 9
CVE-2019-2046   A-117556220  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2047   A-117607414  RCE    Critical   7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2051   A-117555811  ID     High       7.0, 7.1.1, 7.1.2, 8.0, 8.1, 9
CVE-2019-2052   A-117556606  ID     High       7.0, 7.1.1, 7.1.2, 8.1, 9
CVE-2019-2053   A-122074159  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-2019-2049   A-120445479  EoP    High       9
CVE-2019-2050   A-121327323  EoP    High       8.0, 8.1, 9

Change-Id: I636a1c0b84dd78244596cb9ea9be24d5d56b5163