WIP: example void dataset descriptor for openfmri ds001

This is an example dataset descriptor using the [VoID vocabulary](http://www.w3.org/TR/void/).

We currently use only [General Dataset Metadata](http://www.w3.org/TR/void/#metadata), which will extended to use more domain specific neuroinformatics vocabulary.

The file is written using the [Turtle](http://www.w3.org/TR/turtle/) serialization of [RDF](http://www.w3.org/RDF/)