Class to provide the parsing framework for parsing metadata files.
This will support parsing of any metadata files where the resultant object is
derived from org.jpox.metadata.MetaData, so can be used on JDO files, ORM files,
JDOQUERY files, JPA files, or "persistence.xml" files.
Parser handler for "persistence.xml" files to convert them into a PersistenceFileMetaData.
Implements DefaultHandler and handles the extracting of MetaData from the
XML elements/attributes.