added tests for load_partitionmap directly on graph
added tests for load_partitionmap directly on graph

F1000Research/khmer,ged-lab/khmer,jas14/khmer,F1000Research/khmer,ged-lab/khmer,souravsingh/khmer,ged-lab/khmer,Winterflower/khmer,souravsingh/khmer,souravsingh/khmer,jas14/khmer,jas14/khmer,F1000Research/khmer,Winterflower/khmer,Winterflower/khmer