Facebook update support

[STRML]

Added update support for Facebook: subsequent logins will update stored access_token and fb metadata.

I noticed the FB data stored by mongoose-auth on first login quickly becomes stale. This addition to findOrCreateUser will update the stored data with new data when available.

I also added an 'isNew' field to the schema as well. This is true if and only if the user is completely fresh. We use this locally for asking the user to verify certain data, e.g. email address.

[STRML]

Using the above code simplifies the example code given for using Facebook and password login simultaneously. See the call to user.updateFBData():

findOrCreateUser: function (session, accessTok, accessTokExtra, fbUser) {
    var promise = this.Promise()
        , User = this.User()();
    User.findById(session.auth.userId, function (err, user) {
      if (err) return promise.fail(err);
      if (!user) {
        User.where('password.email', fbUser.email).findOne( function (err, user) {
          if (err) return promise.fail(err);
          if (!user) {
            User.createWithFB(fbUser, accessTok, accessTokExtra.expires, function (err, createdUser) {
              if (err) return promise.fail(err);
              return promise.fulfill(createdUser);
            });
          } else {
            user.updateFBData(fbUser, accessTok, accessTokExtra, function(err, user){
              if (err) return promise.fail(err);
              promise.fulfill(user);
            });
          }
        });
      } else {
        user.updateFBData(fbUser, accessTok, accessTokExtra, function(err, user){
          if (err) return promise.fail(err);
          promise.fulfill(user);
        });
      }
    });
  return promise; // Make sure to return the promise that promises the user
}