Update NETStandard.Library to 1.6
Update NETStandard.Library to 1.6

We now have API included in NETStandard.Library that has netstandard1.6
specific surface area so we should bump the version of the package to
1.6.

nbarbettini/corefx,stone-li/corefx,shmao/corefx,JosephTremoulet/corefx,zhenlan/corefx,dotnet-bot/corefx,shmao/corefx,Chrisboh/corefx,krk/corefx,DnlHarvey/corefx,ptoonen/corefx,Petermarcu/corefx,nbarbettini/corefx,ptoonen/corefx,seanshpark/corefx,twsouthwick/corefx,dhoehna/corefx,rjxby/corefx,YoupHulsebos/corefx,krytarowski/corefx,mazong1123/corefx,marksmeltzer/corefx,marksmeltzer/corefx,Ermiar/corefx,parjong/corefx,rahku/corefx,ViktorHofer/corefx,zhenlan/corefx,jlin177/corefx,Jiayili1/corefx,rahku/corefx,richlander/corefx,wtgodbe/corefx,ellismg/corefx,iamjasonp/corefx,mazong1123/corefx,tijoytom/corefx,weltkante/corefx,weltkante/corefx,dotnet-bot/corefx,ericstj/corefx,mmitche/corefx,dotnet-bot/corefx,zhenlan/corefx,lggomez/corefx,alphonsekurian/corefx,billwert/corefx,manu-silicon/corefx,billwert/corefx,seanshpark/corefx,iamjasonp/corefx,Jiayili1/corefx,the-dwyer/corefx,dotnet-bot/corefx,jlin177/corefx,jlin177/corefx,Chrisboh/corefx,rubo/corefx,rjxby/corefx,Ermiar/corefx,billwert/corefx,jhendrixMSFT/corefx,DnlHarvey/corefx,the-dwyer/corefx,nchikanov/corefx,mmitche/corefx,fgreinacher/corefx,dhoehna/corefx,manu-silicon/corefx,shimingsg/corefx,wtgodbe/corefx,richlander/corefx,MaggieTsang/corefx,iamjasonp/corefx,ericstj/corefx,billwert/corefx,weltkante/corefx,shimingsg/corefx,elijah6/corefx,manu-silicon/corefx,Ermiar/corefx,billwert/corefx,YoupHulsebos/corefx,rjxby/corefx,stephenmichaelf/corefx,mazong1123/corefx,jhendrixMSFT/corefx,shmao/corefx,elijah6/corefx,dotnet-bot/corefx,ericstj/corefx,gkhanna79/corefx,twsouthwick/corefx,mmitche/corefx,stone-li/corefx,krytarowski/corefx,ViktorHofer/corefx,elijah6/corefx,Petermarcu/corefx,seanshpark/corefx,ellismg/corefx,stephenmichaelf/corefx,ericstj/corefx,MaggieTsang/corefx,jhendrixMSFT/corefx,nbarbettini/corefx,the-dwyer/corefx,nchikanov/corefx,mmitche/corefx,gkhanna79/corefx,tijoytom/corefx,stephenmichaelf/corefx,lggomez/corefx,fgreinacher/corefx,gkhanna79/corefx,ellismg/corefx,parjong/corefx,alexperovich/corefx,YoupHulsebos/corefx,Jiayili1/corefx,axelheer/corefx,wtgodbe/corefx,yizhang82/corefx,marksmeltzer/corefx,alphonsekurian/corefx,MaggieTsang/corefx,ViktorHofer/corefx,rubo/corefx,shimingsg/corefx,seanshpark/corefx,jlin177/corefx,ravimeda/corefx,nchikanov/corefx,krytarowski/corefx,Ermiar/corefx,nbarbettini/corefx,elijah6/corefx,ViktorHofer/corefx,manu-silicon/corefx,dotnet-bot/corefx,the-dwyer/corefx,twsouthwick/corefx,ptoonen/corefx,Petermarcu/corefx,marksmeltzer/corefx,Chrisboh/corefx,shmao/corefx,nbarbettini/corefx,stone-li/corefx,ptoonen/corefx,tijoytom/corefx,krk/corefx,krytarowski/corefx,weltkante/corefx,ptoonen/corefx,rubo/corefx,Ermiar/corefx,dsplaisted/corefx,krk/corefx,mmitche/corefx,alexperovich/corefx,tijoytom/corefx,gkhanna79/corefx,BrennanConroy/corefx,parjong/corefx,marksmeltzer/corefx,rahku/corefx,jlin177/corefx,Chrisboh/corefx,elijah6/corefx,YoupHulsebos/corefx,iamjasonp/corefx,rjxby/corefx,cydhaselton/corefx,rubo/corefx,ericstj/corefx,jlin177/corefx,rjxby/corefx,YoupHulsebos/corefx,rahku/corefx,MaggieTsang/corefx,the-dwyer/corefx,Petermarcu/corefx,Ermiar/corefx,wtgodbe/corefx,tijoytom/corefx,ViktorHofer/corefx,nchikanov/corefx,nchikanov/corefx,BrennanConroy/corefx,manu-silicon/corefx,JosephTremoulet/corefx,stephenmichaelf/corefx,nbarbettini/corefx,wtgodbe/corefx,lggomez/corefx,parjong/corefx,gkhanna79/corefx,cydhaselton/corefx,Jiayili1/corefx,parjong/corefx,ellismg/corefx,dhoehna/corefx,shimingsg/corefx,ericstj/corefx,cydhaselton/corefx,rahku/corefx,marksmeltzer/corefx,alphonsekurian/corefx,ptoonen/corefx,axelheer/corefx,zhenlan/corefx,shmao/corefx,seanshpark/corefx,shimingsg/corefx,cydhaselton/corefx,BrennanConroy/corefx,dhoehna/corefx,lggomez/corefx,Ermiar/corefx,shimingsg/corefx,YoupHulsebos/corefx,lggomez/corefx,alexperovich/corefx,ravimeda/corefx,stone-li/corefx,DnlHarvey/corefx,stone-li/corefx,shimingsg/corefx,dhoehna/corefx,mmitche/corefx,tijoytom/corefx,fgreinacher/corefx,krk/corefx,cydhaselton/corefx,wtgodbe/corefx,fgreinacher/corefx,yizhang82/corefx,dotnet-bot/corefx,gkhanna79/corefx,alphonsekurian/corefx,ravimeda/corefx,MaggieTsang/corefx,ViktorHofer/corefx,stephenmichaelf/corefx,krytarowski/corefx,alexperovich/corefx,rahku/corefx,marksmeltzer/corefx,twsouthwick/corefx,tijoytom/corefx,cydhaselton/corefx,JosephTremoulet/corefx,ptoonen/corefx,Chrisboh/corefx,iamjasonp/corefx,JosephTremoulet/corefx,JosephTremoulet/corefx,yizhang82/corefx,stephenmichaelf/corefx,cydhaselton/corefx,zhenlan/corefx,Petermarcu/corefx,yizhang82/corefx,alphonsekurian/corefx,ellismg/corefx,mazong1123/corefx,mazong1123/corefx,krk/corefx,dsplaisted/corefx,alphonsekurian/corefx,weltkante/corefx,jhendrixMSFT/corefx,JosephTremoulet/corefx,krytarowski/corefx,iamjasonp/corefx,Jiayili1/corefx,axelheer/corefx,rjxby/corefx,elijah6/corefx,yizhang82/corefx,richlander/corefx,gkhanna79/corefx,jhendrixMSFT/corefx,krytarowski/corefx,alexperovich/corefx,axelheer/corefx,ravimeda/corefx,alphonsekurian/corefx,zhenlan/corefx,Petermarcu/corefx,jlin177/corefx,Jiayili1/corefx,shmao/corefx,iamjasonp/corefx,stone-li/corefx,lggomez/corefx,nbarbettini/corefx,weltkante/corefx,krk/corefx,axelheer/corefx,manu-silicon/corefx,stephenmichaelf/corefx,manu-silicon/corefx,stone-li/corefx,yizhang82/corefx,YoupHulsebos/corefx,mmitche/corefx,jhendrixMSFT/corefx,the-dwyer/corefx,axelheer/corefx,dhoehna/corefx,zhenlan/corefx,seanshpark/corefx,alexperovich/corefx,elijah6/corefx,wtgodbe/corefx,weltkante/corefx,DnlHarvey/corefx,Chrisboh/corefx,billwert/corefx,twsouthwick/corefx,mazong1123/corefx,richlander/corefx,richlander/corefx,mazong1123/corefx,twsouthwick/corefx,Petermarcu/corefx,yizhang82/corefx,parjong/corefx,ravimeda/corefx,seanshpark/corefx,ericstj/corefx,ViktorHofer/corefx,twsouthwick/corefx,DnlHarvey/corefx,krk/corefx,alexperovich/corefx,nchikanov/corefx,ellismg/corefx,JosephTremoulet/corefx,DnlHarvey/corefx,rjxby/corefx,rahku/corefx,MaggieTsang/corefx,richlander/corefx,dsplaisted/corefx,rubo/corefx,Jiayili1/corefx,DnlHarvey/corefx,parjong/corefx,lggomez/corefx,MaggieTsang/corefx,billwert/corefx,richlander/corefx,ravimeda/corefx,the-dwyer/corefx,shmao/corefx,dhoehna/corefx,nchikanov/corefx,jhendrixMSFT/corefx,ravimeda/corefx