dataretriever: Fix missing import in GigaPan module on Python 2.5
dataretriever: Fix missing import in GigaPan module on Python 2.5

cmusatyalab/opendiamond,cmusatyalab/opendiamond,cmusatyalab/opendiamond,cmusatyalab/opendiamond,cmusatyalab/opendiamond