Update to Bukkit 1.7.8-R0.1, format source, organize imports

Signed-off-by: JWhy <jwhy@jwhy.de>
Allow multiple join fireworks in config

Signed-off-by: JWhy <jwhy@jwhy.de>
Improve config (delay in seconds, renamed firework styles)
Release build 0.4

Signed-off-by: JWhy <jwhydev@jwhy.de>