The Download group of packets was in desperate need for a restructuring.
Now, instead of using `DownloadServerList` to list everything, different object types now are downloaded through their own seperate packets. (Improving network efficiency)
This commit removes the org.JSON library where alternatives are already provided (Bungee & Bukkit provide Gson). This change was made to improve compatability with BungeeCord plugins and reduce file sizes.
This means big changes to the SubData API, which heavily relied on org.JSON. Now we submit our data through YAMLSection to be converted and sent over the network.
This is how SubServers will implement the Validator API that I suggested. I had to make some assumptions though (like how I don't expect BungeeCord's api to have a setTabValidator() method).
