SSL/TLS MitM vulnerability due to insecure defaults

All versions of rust-openssl prior to 0.9.0 contained numerous insecure defaults
including off-by-default certificate verification and no API to perform hostname
verification.

Unless configured correctly by a developer, these defaults could allow an attacker
to perform man-in-the-middle attacks.

The problem was addressed in newer versions by enabling certificate verification
by default and exposing APIs to perform hostname verification. Use the
SslConnector and SslAcceptor types to take advantage of these new features
(as opposed to the lower-level SslContext type).