Various ItemMeta fixes.

Fixes BUKKIT-3408, BUKKIT-3190, BUKKIT-3191, BUKKIT-3407

These changes relate mostly to semantical changes for serialization
contract, exception of changing the map scaling value from byte to boolean,
what it should have been in the first place. Appropriate unit tests were
added for CraftMapMeta, as they were missing.
Reapply diffs of MinecraftServer on mc-dev. Fixes BUKKIT-3378