We should try to make the v2 of artifact the default one ASAP. Thus we need to make sure v2 is the default one used. We should also allow building v1 artifact (passing an option to mender-artifact using Yocto), but there should be a warning when v1 is used.

At the moment if no signing key is provided, we will build v1 artifact by default. If there is a key, v2 is used.