Support POST methods on any api call, allow overriding access tokens, support for app sessions

[tarqd]

Basically I've renamed post() to postFeed to make room for a method that allows you to POST to any graph api.

Example (uploading a picture from a url)

req.facebook.post('/me/photos', { name: 'Cool picture', url: 'http://example.com/example.png' } ,function(err, result){
     console.log('result from api : ', err, result);
});

App session support works as follows (sending a notification requires an app access token not a user access token)

  req.facebook.appSession(function(err, session){
    session.post('/1234/notifications', {href: '', template: 'Notification from app!'}, function(err, result){
      res.send("Sent notification to uid 1234!");
    });
  });

I also made it so when there's an API error it wraps up in an error object (FacebookApiError) which inherits from Error

// assume an error occurs
req.facebook.get('/me/friends', function(err, friends){
     if(err){
        console.log(err.message);
        console.log(err.type);
        console.log(err.code);
     }
});

[tarqd]

Any word on this?