It's as simple as a plugin can get. It was originally a plugin to stop horse breeding on skyblock, but it turned into a total mob control type plugin. It disallows mobs from spawning from anything but eggs (disables chunk spawning).
This allows for a farming economy on skyblock, and allows for steep pricing on mob eggs. If mobs could just spawn randomly, there'd be no reason to buy eggs at the market!
While I was disabling breeding, I figured it would also be a good idea for a catch-all on banned mobs, like an enderdragon, pigmen, or Iron Golems. This stops iron/gold farming in skyblock too. All of this is to ensure a working economy.
Just install the jar. Currently there is no configuration as this is a dead-simple plugin for a specific server.