Announce not supported over BungeeCord

[lukechatton]

The announce backend is currently querying info through the server list pings. This causes issues when working with BungeeCord since Bukkit servers are hidden away.

Integration into BungeeCord would be much easier to work with if PGM info was relayed over http separate from the server list ping.

Alternatively, you could make the server-host value be display-only. Right now it looks like the backend is using the specified hostname for querying. If we could specify a query-host in addition to the server-host, I'm sure people wouldn't have issues allowing oc.tc past firewalls.