[412917] EcorePrimitiveTypes has no URI
https://bugs.eclipse.org/bugs/show_bug.cgi?id=412917

Updated the Eclipse-defined UML resources to specify package URIs corresponding to the namespace URIs of their Ecore definitions, where applicable.  The Ecore/Java/XML primitive types library models are not generated to Ecore, so these merely follow the convention of the UML primitive types' namespace URI.