Ignoring the missing type RDF error for the page under testing's url.

Ignoring the missing type RDF error for the page under testing's url.

When testing the stylesheet gets attached to the pages url. All
the meaningful information about the sample or experiment still
gets added to the right <host>/<category>/<id> pages,
unfortunately that means the page url doesn't have a type which
caused _validate_types to toss an error.

I'd previously fixed it by testing for the error message and
filtering it out from the test code, but that didn't work on
ubuntu 10.04 as the error message changes slightly with the
older version of redland rdf.

This version changes the sparql query to ignore the case
where the predicate is a stylesheet and there's no type.