crypto: check protocol version at handshake header

Just seen todo in `node_crypto_clienthello.cc` and checking those protocol versions of `hello` messages:

* `{0x00, 0x02}`: SSLv2

* `{0x03, 0x00}`: SSLv3

* `{0x03, 0x01}`: TLS 1.0

* `{0x03, 0x02}`: TLS 1.1

* `{0x03, 0x03}`: TLS 1.2


/cc @indutny