auth
auth/.hgignore
Enable CSRF protection, add expiration to sessions. Sessions gain a CSRF token, which is passed as a parameter to the login page. The login page now checks for that CSRF token, and logs a CSRF attempt if the token does not match. I also added an expiration to sessions, so they don't last forever. Sessions should be pretty short--we just need to stay logged in for long enough to approve the OAuth request. Everything after that should be cookie based. Finally, I added a configuration parameter to control whether the session cookie should be set to Secure, requiring the use of HTTPS. For production use, this flag is a requirement, but it makes testing extremely difficult, so we need a way to disable it.