Detect Android devices vulnerable to CVE-2011-1823

This change does two things:
1) Adds a new CTS test category called "security", to centralize test
for security bugs, and
2) Adds a test for CVE-2011-1823, the vold exploit discovered by
Sebastian Krahmer, available at
http://c-skills.blogspot.com/2011/04/yummy-yummy-gingerbreak.html

See also http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2011-1823

Bug: 4328371
Change-Id: Iab98d71c2cda24c4a017c6848fac4368a4ad2fd8