Add capability to specify the ssl version to use

This allows a workaround for an issue with Ubuntu 12.04 openssl. Issue is talked about at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=665452

A client can now pass which ssl_version they want to use explicitly rather than relying upon defaults. Sending :ssl_version => :SSLv3 will work around the issue above.