Add VideoStreamManager for keeping track of active streams

The stream manager should help prevent zombie processes and can later be
used for stopping video streams if the user exits the video before
finishing for example.

src/data/mod.rs

@@ -1,9 +1,9 @@
 use std::str::FromStr;
 
-use actix_web::{dev, Error, FromRequest, http::header, HttpRequest};
 use actix_web::error::ErrorUnauthorized;
+use actix_web::{dev, http::header, Error, FromRequest, HttpRequest};
 use futures::future::{err, ok, Ready};
-use jsonwebtoken::{Algorithm, decode, DecodingKey, Validation};
+use jsonwebtoken::{decode, Algorithm, DecodingKey, Validation};
 use serde::{Deserialize, Serialize};
 
 #[derive(Serialize)]