A bug fix and a new feature

Hello,
I tried to improve your code. Those are the changes:
- Un-compressed the code for better maintainability
- Fixed the logout feature, that was not working
- Added an initial implementation of the equivalent of FB.ui of the original Facebook Javascript SDK. For now you can only use the "feed" feature to post contents
-Updated the readme with a little tutorial of that new feature

I hope that it can be useful.