This makes the `verify_ssl` setting function. It also adds a new
setting `ssl_version` which lets you choose the SSL/TLS version
to handshake.

This test suite will test all permutations of these TLS/SSL versions and
expect aligned versions to succeed and misaligned versions to fail.

'aligned' means both client and server are choosing the same TLS/SSL
protocol version. 'misaligned' means they choose different versions.
Example, a TLS v1.1 client would reject an SSLv3 server.

I'm having trouble generating SSL certificates from within JRuby that
JRuby can use. I'd get this error from the client:

> OpenSSL::SSL::SSLError: Received fatal alert: internal_error

Upon deeper inspection, I'd see this on the server side:

> OpenSSL::SSL::SSLError: java.io.IOException: Invalid encoding of
AuthorityKeyIdentifierExtension.

MRI passes the tests where JRuby does not. Additionally, openssl
s_client seems happy to serve with the same certificate that JRuby
doesn't like. Weird.

For now, we'll hard-code some basic certificates until I can find a
workaround or fix it in JRuby.