Add tests for signed and unsigned model checkers
Add tests for signed and unsigned model checkers

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