Changed SSL protocol options.

TODO: Update options in docs.
Q: Why does client_cert_tool.py seem to allow SSLv3?
  - Set server to only supports sslv3.
  - Set client to *not* support sslv3.
  - Connection still works?
  - `openssl s_client -connect host:port -tls1` fails.
  - `openssl s_client -connect host:port -tls1_1` fails.
  - `openssl s_client -connect host:port -tls1_2` fails.
  - `openssl s_client -connect host:port -ssl3` succeeds.