added test for multi-join in rdflite
added test for multi-join in rdflite

net7/ActiveRDF,mauriciobomfim/ActiveRDF,net7/ActiveRDF,net7/ActiveRDF,mauriciobomfim/ActiveRDF,ActiveRDF/ActiveRDF,net7/ActiveRDF,mauriciobomfim/ActiveRDF,ActiveRDF/ActiveRDF,ActiveRDF/ActiveRDF