Delay first place announcements in multiplayer matches

[cmyui]

This is actually a problem with every server implementation so far I believe; if multiple players achieve first place on a map, it'll announce all of them in the order that it gets the scores in.

The server should enqueue a task once the server knows the match has ended to re-check the first place in a few seconds (~5-10 should be fine), and announce it if it's been set.