Go 1.8 includes "crypto/tls: disable CBC cipher suites with SHA-256 by
default." which breaks the "TLS12-AES128-SHA256-server" test (among
others). Since this was fixed upstream (by removing the CBC tests), just
update the vendored copy using:
gvt update github.com/google/boringssl/ssl/test
Removed tests from config.json that are no longer present while at it.
