Add Apache config for newer distros

The previous version of secure-ssl.conf in this repo was only for older
systems, it used an old set of allowed SSL protocols and ciphers. This
commit adds the config used on newer servers, checking the distro version
to see which config to use.

The only exceptions are library and stumptown, which have newer versions
of Apache and OpenSSL, but use the older SSL config. I added a hostvar to
formalize this deviation, but we should probably make them use the newer
config too. I just didn't want to change anything with this playbook,
only document the current state.