Have you tried the Facebook registration plugin?
I have tried that recently. It is simply to use and provide a quick way for sites to integration Facebook user account into their site level registration flow.
The only comment that I have is that it would be best if Faecbook can integrate the handling of the extension permission in this plugin. We can specify the permission list to be requested from the user when using the Facebook Login button… but this is not available for the registration plugin.
Right now, what I am doing is to request for the additional permission at the time Facebook forwards the registration request to my app.