Axe of Revenge

Attempted to add a battleaxe, but weapon speed seems difficult to do, making different melee weapon types a lot harder. In my frustration, I added the Axe of Revenge,
which deals more damage the lower the player's health is (at 1 HP a player can deal 13.5 hearts  of damage)
Merge branch '1.7.2' of https://github.com/jaltekruse/WhatEverYouWantMinecraft into 1.7.2