Added OMEXML Metadata model

Added parallel ome.xml.* classes to create an OME-XML SCIFIO Metadata
and Format.

Created translators to and from relevant formats, for converting to
OME-XML.

Added the OME-XML model resources.
Merge branch 'ome-xml-support'

Added support for extracting OME-XML from SCIFIO formats via translation.