Added fix for #21
Added fix for #21

alabid/blinkdb,sameeragarwal/blinkdb_dev,sjyk/sampleclean,mapr/shark,sameeragarwal/blinkdb,amplab/shark,lzshlzsh/shark,amplab/shark,sameeragarwal/blinkdb,mattyb149/blinkdb,sameeragarwal/blinkdb_dev,vax11780/shark,sameeragarwal/blinkdb,mattyb149/blinkdb,sjyk/sampleclean,sameeragarwal/blinkdb_dev,vax11780/shark,mattyb149/blinkdb,alabid/blinkdb,lzshlzsh/shark,vax11780/shark,mapr/shark,mapr/shark,alabid/blinkdb,lzshlzsh/shark,amplab/shark,sjyk/sampleclean