Add system for item update requests (and add it to the front page)

[karashiiro]

This may be yet another variant of #208. It implies some kind of system that increments a server-side counter for top items to be updated on a world or data center, which resets to 0 once the item is actually updated on the world or data center. To prevent abuse, this needs be restricted to users with an account, which means resolving #200.

[karashiiro]

#200 is now resolved, this can be worked on at some point, now.