csgo-server aur package

This PKGBUILD downloads and packages a CS:GO game server using steamcmd.

caveats

• run makepkg with PKGEXT=.pkg.tar, or you will spend hours compressing 13GB of mostly already compressed data
• run the server via the included unit file
• only the csgo-server user, created by this package, can run the game server due to permission issues (to be fixed)