Add 2 UnitsFactory implementations

Like the ColorFactory classes, one in rendering and one in blitz,
the UnitsFactory implementations should be the central location
for creating unit objects and converting back and forth between
either the ome.model or the omero.model representations and those
in ome.xml.
Include generated ome-xml source in Eclipse
Convert all Length fields in ome and omero models

This should bring the OMERO classes up-to-date with regard
to the Bio-Formats length unit changes. Modifications stop
in the pojo data objects by marking methods as @Deprecated
which need to have a unit added to their signature.  Those
methods which specified in their javadoc that a given unit
was to be used are not marked as deprecated. The factories
in the rendering/ and blitz/ components should contain all
helpers for converting and making units.
5.1DEV__13: add schema files sans upgrade