Support .well-known/change-password

There is a recent submission to the .well-known URI registry for change-password. The purpose of this URI is simply to take the user directly to a page for changing his/her password. It occurred to me that this is an almost trivial drop-in for this module, so I've made a patch to support it.

If the user is already logged in, the link redirects to the change-password page, if not it goes to the login page, and on successful login then goes to the change-password page.

It consists simply of a menu router item and a small callback function.

Enjoy!