added FACEBOOK_APP_ID and FACEBOOK_APP_SECRET as kwargs

[raduhek]

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.