Cleanup Average tests in System.Linq
Cleanup Average tests in System.Linq

- Take advantage of xunit
- Make it easier to add new tests
- Rename tests to follow guidelines

richlander/corefx,manu-silicon/corefx,alexperovich/corefx,ViktorHofer/corefx,nbarbettini/corefx,MaggieTsang/corefx,DnlHarvey/corefx,seanshpark/corefx,shmao/corefx,krytarowski/corefx,ericstj/corefx,rubo/corefx,elijah6/corefx,krytarowski/corefx,ericstj/corefx,axelheer/corefx,tijoytom/corefx,marksmeltzer/corefx,ViktorHofer/corefx,ravimeda/corefx,rahku/corefx,Priya91/corefx-1,ericstj/corefx,yizhang82/corefx,the-dwyer/corefx,axelheer/corefx,JosephTremoulet/corefx,dsplaisted/corefx,stephenmichaelf/corefx,twsouthwick/corefx,iamjasonp/corefx,dotnet-bot/corefx,dhoehna/corefx,lggomez/corefx,richlander/corefx,nbarbettini/corefx,Petermarcu/corefx,Jiayili1/corefx,MaggieTsang/corefx,iamjasonp/corefx,parjong/corefx,axelheer/corefx,dhoehna/corefx,parjong/corefx,krytarowski/corefx,weltkante/corefx,Chrisboh/corefx,iamjasonp/corefx,fgreinacher/corefx,alphonsekurian/corefx,krk/corefx,ViktorHofer/corefx,shmao/corefx,marksmeltzer/corefx,elijah6/corefx,seanshpark/corefx,Priya91/corefx-1,Ermiar/corefx,parjong/corefx,yizhang82/corefx,alphonsekurian/corefx,twsouthwick/corefx,dhoehna/corefx,lggomez/corefx,dhoehna/corefx,lggomez/corefx,weltkante/corefx,Priya91/corefx-1,mazong1123/corefx,cydhaselton/corefx,JosephTremoulet/corefx,weltkante/corefx,elijah6/corefx,rahku/corefx,nchikanov/corefx,wtgodbe/corefx,mazong1123/corefx,jhendrixMSFT/corefx,DnlHarvey/corefx,lggomez/corefx,Petermarcu/corefx,wtgodbe/corefx,Petermarcu/corefx,stephenmichaelf/corefx,Jiayili1/corefx,gkhanna79/corefx,dotnet-bot/corefx,twsouthwick/corefx,alphonsekurian/corefx,ericstj/corefx,rubo/corefx,yizhang82/corefx,MaggieTsang/corefx,richlander/corefx,stone-li/corefx,DnlHarvey/corefx,Jiayili1/corefx,jlin177/corefx,cydhaselton/corefx,alexperovich/corefx,YoupHulsebos/corefx,gkhanna79/corefx,ravimeda/corefx,seanshpark/corefx,rubo/corefx,Chrisboh/corefx,jlin177/corefx,ptoonen/corefx,YoupHulsebos/corefx,billwert/corefx,shimingsg/corefx,JosephTremoulet/corefx,shimingsg/corefx,mmitche/corefx,Jiayili1/corefx,parjong/corefx,yizhang82/corefx,dsplaisted/corefx,billwert/corefx,weltkante/corefx,fgreinacher/corefx,Ermiar/corefx,alphonsekurian/corefx,mazong1123/corefx,ericstj/corefx,wtgodbe/corefx,stephenmichaelf/corefx,wtgodbe/corefx,ellismg/corefx,shmao/corefx,nbarbettini/corefx,cydhaselton/corefx,stephenmichaelf/corefx,manu-silicon/corefx,cydhaselton/corefx,ptoonen/corefx,dotnet-bot/corefx,YoupHulsebos/corefx,Chrisboh/corefx,Chrisboh/corefx,jhendrixMSFT/corefx,manu-silicon/corefx,BrennanConroy/corefx,shmao/corefx,JosephTremoulet/corefx,alexperovich/corefx,jlin177/corefx,yizhang82/corefx,ericstj/corefx,zhenlan/corefx,ericstj/corefx,rjxby/corefx,dotnet-bot/corefx,ViktorHofer/corefx,stephenmichaelf/corefx,BrennanConroy/corefx,parjong/corefx,BrennanConroy/corefx,billwert/corefx,krk/corefx,mazong1123/corefx,ellismg/corefx,mmitche/corefx,nchikanov/corefx,manu-silicon/corefx,parjong/corefx,ptoonen/corefx,fgreinacher/corefx,manu-silicon/corefx,alphonsekurian/corefx,zhenlan/corefx,YoupHulsebos/corefx,rahku/corefx,rahku/corefx,Chrisboh/corefx,Petermarcu/corefx,billwert/corefx,ViktorHofer/corefx,krk/corefx,Ermiar/corefx,iamjasonp/corefx,twsouthwick/corefx,ptoonen/corefx,twsouthwick/corefx,lggomez/corefx,elijah6/corefx,rahku/corefx,rjxby/corefx,mazong1123/corefx,shimingsg/corefx,cydhaselton/corefx,the-dwyer/corefx,DnlHarvey/corefx,Petermarcu/corefx,ellismg/corefx,jhendrixMSFT/corefx,richlander/corefx,shmao/corefx,elijah6/corefx,the-dwyer/corefx,the-dwyer/corefx,rubo/corefx,krk/corefx,rjxby/corefx,ellismg/corefx,Jiayili1/corefx,gkhanna79/corefx,ravimeda/corefx,stephenmichaelf/corefx,nchikanov/corefx,ViktorHofer/corefx,billwert/corefx,krk/corefx,mazong1123/corefx,ptoonen/corefx,jlin177/corefx,Ermiar/corefx,parjong/corefx,rubo/corefx,jhendrixMSFT/corefx,Petermarcu/corefx,Priya91/corefx-1,mmitche/corefx,rahku/corefx,dotnet-bot/corefx,dsplaisted/corefx,gkhanna79/corefx,richlander/corefx,yizhang82/corefx,adamralph/corefx,nbarbettini/corefx,stone-li/corefx,shmao/corefx,Chrisboh/corefx,zhenlan/corefx,wtgodbe/corefx,Ermiar/corefx,wtgodbe/corefx,MaggieTsang/corefx,seanshpark/corefx,wtgodbe/corefx,Priya91/corefx-1,cydhaselton/corefx,ellismg/corefx,weltkante/corefx,stone-li/corefx,rjxby/corefx,cydhaselton/corefx,rjxby/corefx,MaggieTsang/corefx,YoupHulsebos/corefx,mmitche/corefx,tijoytom/corefx,shimingsg/corefx,weltkante/corefx,zhenlan/corefx,Petermarcu/corefx,marksmeltzer/corefx,nbarbettini/corefx,rjxby/corefx,jhendrixMSFT/corefx,mmitche/corefx,ellismg/corefx,JosephTremoulet/corefx,lggomez/corefx,alphonsekurian/corefx,twsouthwick/corefx,shimingsg/corefx,marksmeltzer/corefx,seanshpark/corefx,Jiayili1/corefx,JosephTremoulet/corefx,adamralph/corefx,yizhang82/corefx,dotnet-bot/corefx,jlin177/corefx,krytarowski/corefx,jhendrixMSFT/corefx,rjxby/corefx,manu-silicon/corefx,krk/corefx,nchikanov/corefx,Ermiar/corefx,Ermiar/corefx,krytarowski/corefx,marksmeltzer/corefx,manu-silicon/corefx,iamjasonp/corefx,ViktorHofer/corefx,richlander/corefx,tijoytom/corefx,stone-li/corefx,nbarbettini/corefx,jhendrixMSFT/corefx,nchikanov/corefx,krk/corefx,iamjasonp/corefx,JosephTremoulet/corefx,DnlHarvey/corefx,DnlHarvey/corefx,the-dwyer/corefx,MaggieTsang/corefx,billwert/corefx,rahku/corefx,mazong1123/corefx,ptoonen/corefx,gkhanna79/corefx,fgreinacher/corefx,ravimeda/corefx,krytarowski/corefx,richlander/corefx,zhenlan/corefx,ravimeda/corefx,zhenlan/corefx,ravimeda/corefx,iamjasonp/corefx,nchikanov/corefx,weltkante/corefx,stone-li/corefx,krytarowski/corefx,dhoehna/corefx,alexperovich/corefx,the-dwyer/corefx,billwert/corefx,ravimeda/corefx,shmao/corefx,Priya91/corefx-1,zhenlan/corefx,marksmeltzer/corefx,stone-li/corefx,tijoytom/corefx,alphonsekurian/corefx,nbarbettini/corefx,dhoehna/corefx,tijoytom/corefx,stone-li/corefx,marksmeltzer/corefx,elijah6/corefx,elijah6/corefx,YoupHulsebos/corefx,nchikanov/corefx,shimingsg/corefx,dotnet-bot/corefx,tijoytom/corefx,ptoonen/corefx,gkhanna79/corefx,twsouthwick/corefx,gkhanna79/corefx,Jiayili1/corefx,alexperovich/corefx,adamralph/corefx,mmitche/corefx,MaggieTsang/corefx,dhoehna/corefx,axelheer/corefx,lggomez/corefx,jlin177/corefx,axelheer/corefx,seanshpark/corefx,alexperovich/corefx,alexperovich/corefx,jlin177/corefx,shimingsg/corefx,stephenmichaelf/corefx,YoupHulsebos/corefx,DnlHarvey/corefx,mmitche/corefx,the-dwyer/corefx,axelheer/corefx,tijoytom/corefx,seanshpark/corefx