This project has moved to Planet Minecraft.
This data pack gives the player the heads of mobs they kill, when they deal the killing blow with a Golden Axe. It supports all varieties of animals, and villager professions!
The kill detection and head giving operate without affecting any loot tables, so it won't conflict with any other data pack that modifies loot tables.
More information about data packs and how to use them can be found on the official Minecraft Wiki.