added join_pe to master
added join_pe to master

F1000Research/khmer,souravsingh/khmer,ged-lab/khmer,kdmurray91/khmer,Winterflower/khmer,kdmurray91/khmer,jas14/khmer,Winterflower/khmer,jas14/khmer,kdmurray91/khmer,souravsingh/khmer,jas14/khmer,F1000Research/khmer,ged-lab/khmer,souravsingh/khmer,Winterflower/khmer,F1000Research/khmer,ged-lab/khmer