data/steps: dont start step at creation

We need to create steps at builderfactory time, so that they
can be displayed in the UI

Signed-off-by: Pierre Tardy <pierre.tardy@intel.com>
service: fix import failure in case of missing endpoint

This happens when switching branches that does not contain
a previously "setup.py develop"ed plugin

Signed-off-by: Pierre Tardy <pierre.tardy@intel.com>