Fix OpenSSL error when using HTTPS

There was an SSL handshake failure that occurred when attempting to perform an HTTP request to certain https addresses. I've been using `rust-http` in my version manager for the Rust compiler, and when I attempted to perform a HTTP GET on any Rust download the connection would fail with an OpenSSL error. (For example: `https://static.rust-lang.org/*`)

I cleaned up the error messages in `rust-openssl` to make it more clear what was happening and then diagnosed that without the SNI the request would fail. It is a very simple fix, and setting the hostname on the SSL session seemed to be enough.

The code that *was* failing can be found here: https://github.com/jroesch/rustv/blob/master/src/rustv/version.rs#L57.
If `_host` is being used, it should be changed to `host`.