tidy up osgi test bundles, in prep for writing more bundles and more tests
OSGi catalog item test (see full msg for details)

Add some more OSGi test bundles - see OsgiTestResources.
Write lots more tests of OSGi loading and item ID - in OsgiEntitiesTest.
Also load OSGi on addItem(CatalogItem), and improve OSGi loading error messages when OSGi loading fails.