Add autoConnect option

I am wondering why this has been removed in 1.0. I found it very handy in 0.9. I would like to just grab the instance of `Manager`, attach even listeners and then open the connection.

I know that in docs you are suggesting the following approach:

    var manager = io.Manager('url', { /* options */ });
    var socket = manager.socket('/namespace');
    manager.on('event_name_like_reconnect_attempt', function() {
    }); 

That seems rather silly, because this way it is skipping whole `lookup` mechanics and the manager is not cached. I would have to pass around manager instances in my application on my own. Having `autoConnect` option could be safer and easier way. Am I missing something here ?