Add configurable ssl options for the director nginx

- director.nginx.ssl_prefer_server_ciphers
- director.nginx.ssl_protocols
- director.nginx.ssl_ciphers
- New defaults dissallow SSLv3
- New defaults use ciphers from Mozilla's "modern" recommendation

[#80756396]

Signed-off-by: Zachary Auerbach <zak@zaksoup.com>
Enable SSL for integration tests (director nginx)

Signed-off-by: Zachary Auerbach <zak@zaksoup.com>
Bump bosh-agent to disable SSLv3 support (agent's micro server)

[#80756396]

Signed-off-by: Zachary Auerbach <zak@zaksoup.com>