add option to normalize gradients
add option to normalize gradients

lseyesl/neural-style,samim23/neural-style,napsternxg/neural-style,ksemianov/neural-style,PoisonBOx/neural-style,zerolocker/neural-style,panovr/neural-style,panzixiang/neural-style,swn73/neural-style,lipiji/neural-style,mcanthony/neural-style,brunoro/neural-style,bwwyyy/neural-style,bestwpw/neural-style,jcjohnson/neural-style,alcherk/neural-style,Tonsty/neural-style,lgs777/neural-style,onecue/neural-style,TobiasMR/neural-style,hughperkins/neural-style,n1ckfg/neural-style,Theviajerock/neural-style,codeaudit/neural-style,trigrass2/neural-style,horzelski/neural-style,Nigh/neural-style,iporty/neural-style,VaKonS/neural-style,hmandal/neural-style,shenyunhang/neural-style,waythe/neural-style,fugabi/neural-style,sufengniu/neural-style,archesystems/neural-style,neilpanchal/neural-style,Badredapple/neural-style,PaniniGelato/neural-style,avldya/neural-style,kciter/neural-style,islijepcevic/neural-style,shinyvince/neural-style,ChenglongChen/neural-style,AdeDZY/neural-style,zerolocker/neural-style,ericzhouh/neural-style