Datacatalog rendering for 'Source' datacatalogs

Datacatalog for a source is in the release file.
These include references to the urns included in the data catalog.

So, this will need to do some dynamic listing to get the names of the datasets when a user clicks on a source from the about page.

This would be a sparql query to get the approprate datacatalog from the triplestore.

This should use the graph to get the names of the datasets in the data catalog, initially.