added FACEBOOK_APP_ID and FACEBOOK_APP_SECRET as kwargs

Changelog:
 * added `FACEBOOK_APP_ID_KWARGS`, `FACEBOOK_APP_SECRET_KWARGS` and `FACEBOOK_DEFAULT_KWARGS` in `django_facebook/settings.py`
 * modified functions where `FACEBOOK_APP_ID`, `FACEBOOK_APP_SECRET` and `FACEBOOK_DEFAULT` are used to accept `*args` and `**kwargs` and assign the appropriate value from `kwargs` or `facebook_settings`
 * modified `FacebookAuthorization._client_info` to accept `client_id` and `client_secret`. These values are passed from calling functions.