Send quit-package to server on stdout-error

[SvantjeJung]

Change error handling from info! to sending quit-package to server because if there is an error on stdout client will not be able to interact with server anymore. So client program must be closed.

let e = stdout().flush();
match e {
    Ok(_) => {},
    Err(_) => info!("")
}

[SvantjeJung]

Found the following in this rust issue:

print!("Type something: ");
io::stdout().flush().ok().expect("Could not flush stdout");

I think that would be a nicer way to handle flush()-errors.

[LukasKalbertodt]

Well... expect is just unwrap() with custom error message ;)
But sure, flush failing is too unlikely...