Suggested change #10
Description
Just having a play with this and noticed an issue which should be relatively easy to work around, but thought I'd mention it here before offering a pull request in case there's a reason for the current design...
The docs suggest this as a way to mark that the index page has been visited @mark('index:visited', current_user.id) but if the user is not logged in then current_user doesn't have an id attribute.
Might it be better to pass just current_user and let flask-bitmapist decide whether to act on it if it finds an id attribute.
(As an aside, is it possible to make this work with an authenticated redis? I've been trying to pass the password in using the BITMAPIST_REDIS_URL but without any luck)