Replace makeStubMethod with sinon.stub in the bundle importer tests.
Replace makeStubMethod with sinon.stub in the bundle importer tests.

bac/juju-gui,mitechie/juju-gui,mitechie/juju-gui,bac/juju-gui,mitechie/juju-gui,mitechie/juju-gui,bac/juju-gui,bac/juju-gui