Test case rdfa1.1/xhtml1/0029

Hello,

Result of [this test case](https://github.com/rdfa/rdfa.github.io/blob/master/test-suite/test-cases/rdfa1.1/xhtml1/0029.xhtml) should be
```turtle
<http://example.org/foo>
   <http://purl.org/dc/elements/1.1/creator> "Mark Birbeck"^^xsd:string 
```
and not
```turtle
<http://example.org/foo>
   <http://purl.org/dc/elements/1.1/creator> "Mark Birbeck"
```

The sparql file is correct, though.