Fix bug in GET listing api
Fix bug in GET listing api

hoffmabc/openbazaar-go,hoffmabc/openbazaar-go,OpenBazaar/openbazaar-go,OpenBazaar/openbazaar-go,gubatron/openbazaar-go,gubatron/openbazaar-go,gubatron/openbazaar-go,hoffmabc/openbazaar-go,OpenBazaar/openbazaar-go