Add datanucleus to the ivy search path

The latest Hive uses a version of jdo that isn't in the maven
repositories. This patch adds the same datanucleus repository as
Hive so `ant` will find all the right dependencies.
Fix character tokens not being parsed into Avro

Character tokens were set to not have data, which resulted
in single character tokens being dropped when parsed into
Avro. This patch fixes the bug by properly creating a schema
for characters and casting these characters into a Utf8 for
Avro.
Migrated build system from ivy to  maven
Merge pull request #7 from Lab41/maven-update

Update to Maven and Fix CharToken related bug.  LGTM -- mjc
Updates to the POM to address build issues
The pom was missing a repository to fetch the jdo related files, so I added the Datanucleus maven repo.  Also, I added the plugin to force maven to use java 1.6.