feature: add tests for RedHat-based ciphers (6.4+6.5)

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
feature: add tests for RedHat-based macs (6.4+6.5)

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
feature: make sure KEX for RedHat 6.4+6.5 is disabled

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>