Fixing issue with ready event being called too early when opening folders on load 

Fixing the issue with the ready event being called too early when opening folders on load.

I have created a couple of demos - without the state plugin - on my website:
* http://matthewhutton.com/jstree-old/demo/filebrowser/
* http://matthewhutton.com/jstree/demo/filebrowser/

The "old" one is with the latest copy of the code from github, the other is with my change.