allow multiple values for same key in query in lib.url.build()
allow multiple values for same key in query in lib.url.build()

this is also how it is done in base_url()

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