Always consume bonemeal when used on a sapling. Fixes BUKKIT-3755

In Minecraft 1.5 saplings do not grow with a single use of bonemeal anymore.
Our code assumes they will and only takes away bonemeal from the player
when the tree grows successfully (not cancelled by a plugin). Instead we
now always remove a bonemeal even if a plugin is the reason a tree didn't
grow as this matches the vanilla logic more closely.