minecraft-server: version 1.7.5

Signed-off-by: Austin Seipp <aseipp@pobox.com>
nixos: add minecraft-server service

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Merge branch 'minecraft-server' of git://github.com/thoughtpolice/nixpkgs

nixpkgs: add Minecraft Server & a service module