rdfsurveyor should explore named graphs

[jmvanel]

On my SPARQL http://semantic-forms.cc:9112/sparql there is almost nothing in the anonymous graph. rdfsurveyor says: No data in the repository!

NOTE: explanation why all is in named graphs in semantic-forms: https://github.com/jmvanel/semantic_forms/wiki/User_manual#the-rdf-cache-and-database