feature - add horse inventoy

[madtomic]

add donkey inventory to horse, horse inventory would behave like donkey inventory

success: "&2You added a chest to your horse."
error: "&cYou cannot add a chest to your horse."

permission to use
stablemaster.addchest

Reference: https://minecraft.gamepedia.com/Donkey

[RobotoRaccoon]

Vanilla does not support chests on horses. Whilst it's possible to do in the plugin, it's not what this plugin is about. It'll go in the "maybe" pile.