Force item data to use a tag name. Fixes BUKKIT-4809

The recent Minecraft update rendered the
e20e50f85083dc53cb5456254bcf5781ef750daa fix incorrect by adding a
compound name to the base tag in some code. This fix changes all uses
of tag changes to explicitly use a name.
Update maven compiler to 2.3.2

This change removes a redundant addition of source encoding and makes our
compiler match the current maven default. This amends the commit
4775b25a5932a2a24da2c55356936e2f98bff98c

Upstream issue http://jira.codehaus.org/browse/MCOMPILER-70