Move JAXBContext creation into a method
extract writing to its own method
Add oxml.xml from the search servers servlet project
Add the maven-resources-plugin
Add a JSON writer

This uses the same configuration as the one in the search server.

A few methods and attributes on MBXMLWriter had to be made protected to
allow overwriting them.

This doesn't work yet because a few classes from
org.musicbrainz.search.servlet.moxy still need to be ported.