Update STS Tests for Android Security BUG 183613671 and BUG 183963253. Fixes: * Use "feature:" instead of just raw string in tradefed ITestDevice.hasFeature. * Check for permission "SYSTEM_ALERT_WINDOW" in Intrumentation DeviceTest. Bug: 189998250 Test: used test commands in http://ag/15584942 and http://ag/15838396 to verify. Change-Id: I0bb9f63dc5e632fd34dbdd5ff4576573dfb6391c