Update Belief Engine to work with networkx2
Update Belief Engine to work with networkx2

johnbachman/belpy,pvtodorov/indra,bgyori/indra,johnbachman/indra,pvtodorov/indra,sorgerlab/belpy,sorgerlab/indra,pvtodorov/indra,johnbachman/indra,bgyori/indra,johnbachman/indra,johnbachman/belpy,pvtodorov/indra,sorgerlab/indra,johnbachman/belpy,sorgerlab/belpy,sorgerlab/indra,bgyori/indra,sorgerlab/belpy