Function is_upgrade 

pub fn is_upgrade(req: &Request) -> bool

Is this request asking to become a WebSocket?

use majordomus_cli::http::{ws, Request};
let plain = Request::parse_target("GET", "/events", vec![]);
assert!(!ws::is_upgrade(&plain));
let asking = plain.clone().with_headers(vec![
    ("Upgrade".into(), "websocket".into()),
    ("Connection".into(), "Upgrade".into()),
]);
assert!(ws::is_upgrade(&asking));