Allow the disabling of spawn beings always being loaded

While this may not save a large amount of resources by some people's measures, Spigot is quite popular in the low end hardware community (eg, Raspberry Pis) where you need to scrape anything you can get back to keep the server running.

The spawn chunks are a section of 16x16 chunks[0] allocated as close to the world spawn as possible and are always loaded and being ticked. This allows for their removal without using a third party plugin.

[0] http://minecraft.gamepedia.com/Spawn_chunk#Finding_spawn_chunks