Change the rendering method for RDF to stop genshi being so 'helpful'

If using xhtml as the render method with genshi, and it encounters
xml:lang it will also add a lang attribute with the same value. Helpful.

We change the renderer to be xml if rendering rdf

ckan/controllers/package.py

@@ -309,6 +309,9 @@ def read(self, id, format='html'):
         template = self._read_template( package_type )
         template = template[:template.index('.')+1] + format
 
+        if extension == 'rdf':
+            return render( template, method="xml", loader_class=loader)
+
         return render( template, loader_class=loader)