fix bug in setPotential
fix bug in setPotential

arhik/nupic,ywcui1990/nupic,subutai/nupic,EricSB/nupic,neuroidss/nupic,alfonsokim/nupic,numenta/nupic,pulinagrawal/nupic,badlogicmanpreet/nupic,rhyolight/nupic,scottpurdy/nupic,subutai/nupic,numenta/nupic,alfonsokim/nupic,badlogicmanpreet/nupic,pulinagrawal/nupic,neuroidss/nupic,lscheinkman/nupic,rcrowder/nupic,rhyolight/nupic,marionleborgne/nupic,EricSB/nupic,vitaly-krugl/nupic,pulinagrawal/nupic,marionleborgne/nupic,arhik/nupic,subutai/nupic,arhik/nupic,lscheinkman/nupic,ywcui1990/nupic,marionleborgne/nupic,scottpurdy/nupic,rcrowder/nupic,vitaly-krugl/nupic,numenta/nupic,vitaly-krugl/nupic,ywcui1990/nupic,rhyolight/nupic,neuroidss/nupic,rcrowder/nupic,scottpurdy/nupic,alfonsokim/nupic,lscheinkman/nupic,badlogicmanpreet/nupic,EricSB/nupic