Make API similar to FB api, so it can be used as a drop in replacement.

Hi! I found this plugin very useful, especially after struggling a day with the phongegap-facebook-plugin (seems like they are in a big migration currently). The only thing that was missing for me, or a problem for me, is that the API is a little bit differnt from the Facebook API. Since I would like to use this as a drop in replacement for mobile application login, I had to change the API a little bit, else I would have to duplicate all method calls. Now I just need to replace the FB object with the OpenFB object in mobile.

I thought that maybe you might find this code useful, I updated the codebase and the example index.html. I also could update the README.md if you find the changes appealing.