Add AntJPADomainExporter and its test files

Since querydsl-apt's apt-maven-plugin can't generate Querydsl query
types when the JPA metamodel is specified in a mapping file (orm.xml)
instead of using JPA annotations, add a custom Ant task which calls
JPADomainExporter to generate Querydsl query types from the JPA
metamodel in persistence.xml and orm.xml.  Also add test files
(persistence.xml, orm.xml, Departments.java, and
AntJPADomainExporterTest.java) to make sure the Ant task works.