bin/paster index: fix bug if no instance is given
bin/paster index: fix bug if no instance is given

DanielNeugebauer/adhocracy,DanielNeugebauer/adhocracy,SysTheron/adhocracy,phihag/adhocracy,alkadis/vcv,liqd/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,alkadis/vcv,phihag/adhocracy,liqd/adhocracy,SysTheron/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,phihag/adhocracy,liqd/adhocracy,phihag/adhocracy,phihag/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,liqd/adhocracy,SysTheron/adhocracy