Enhance cluster and websocket client

[4t145]

1. refactor websocket client
2. rewrite logics for cluster publish and wait response
3. add async set mode for tardis_static macro

tardis_static! {
    async set some_config: Value;
}

async fn init() {
    ...
    set_some_config(my_value)
}

async fn another_init() {
    let config = some_config().await;
    // will pending until the config have been setted.
}

4. remove the default values for ui/spec/ path in web server config.
5. add some methods for cache client.