Guest access needs to be implemented

The admin users should be able to enable "Guest" access, and then a special Guest account should be created. It should live in the user table but have a random unknown password. It should be saved in the site settings which ID this guest user has. If guest access is disabled, this account just gets disabled (new status), but will be enabled when setting is turned on.

The guest account will be used when someone is viewing a public project that has "guest" as the lowest level of access. Then they should be able to file tickets and comment on tickets, again depending on the .

As part of this, we need to log ip or location of comments, so that we can block abusing IP:s.

Guests should only be allowed to write comments or file tickets every so often. Maybe some sort of backoff.