`connection.join('sessionid')` fixed.

`connection.join('sessionid')` fixed. Now, `onNewSession` will NEVER be
fired if you're calling "join" method whilst passing "string" as
session-id.

```javascript
connection.onNewSession = function(session)
{
    // this code isn't called
    // because "join" method is called
with string-argument
    // you should use "connect" method if you want
"onNewSession" to be fired.

session.join();
};

connection.join('session-id');
```