Remove `deployed_versions` from asset list serializer
Remove `deployed_versions` from asset list serializer

It's very expensive and kills the performance of the asset list view. It's only
needed on the detail serializer.

kobotoolbox/kpi,kobotoolbox/kpi,onaio/kpi,kobotoolbox/kpi,kobotoolbox/kpi,onaio/kpi,onaio/kpi,kobotoolbox/kpi,onaio/kpi