Merge pull request #1628 from reaperhulk/0.7.2-backport-binding

[backport 0.7.2] Add support for querying the negotiated TLS/SSL version.

src/cryptography/hazmat/bindings/openssl/ssl.py

@@ -302,6 +302,7 @@
 long SSL_CTX_get_timeout(const SSL_CTX *);
 
 const SSL_CIPHER *SSL_get_current_cipher(const SSL *);
+int SSL_version(const SSL *);
 
 /* SNI APIs were introduced in OpenSSL 1.0.0.  To continue to support
  * earlier versions some special handling of these is necessary.