dir.props: correctly enclose 'Exists' condition in single quotes
dir.props: correctly enclose 'Exists' condition in single quotes

According to MSDN (http://msdn.microsoft.com/en-us/library/7szfhaft.aspx), the
single quotes can be left off for "simple alphanumeric strings or boolean values".
This is not the case here (it is a property), so we should use single quotes.

Note that MSBuild ignores this, but it results in a parser error on Mono's xbuild.
pallavit/corefx,EverlessDrop41/corefx,vrassouli/corefx,mellinoe/corefx,shiftkey-tester/corefx,vidhya-bv/corefx-sorting,bitcrazed/corefx,viniciustaveira/corefx,khdang/corefx,alexandrnikitin/corefx,twsouthwick/corefx,mellinoe/corefx,Yanjing123/corefx,SGuyGe/corefx,jhendrixMSFT/corefx,richlander/corefx,Chrisboh/corefx,Jiayili1/corefx,tijoytom/corefx,jeremymeng/corefx,FiveTimesTheFun/corefx,stephenmichaelf/corefx,KrisLee/corefx,rjxby/corefx,jlin177/corefx,gregg-miskelly/corefx,janhenke/corefx,ViktorHofer/corefx,wtgodbe/corefx,vs-team/corefx,pgavlin/corefx,elijah6/corefx,MaggieTsang/corefx,cartermp/corefx,CherryCxldn/corefx,vrassouli/corefx,arronei/corefx,nbarbettini/corefx,mokchhya/corefx,bitcrazed/corefx,Petermarcu/corefx,Priya91/corefx-1,fgreinacher/corefx,krk/corefx,Winsto/corefx,rajansingh10/corefx,dhoehna/corefx,nchikanov/corefx,Jiayili1/corefx,DnlHarvey/corefx,stone-li/corefx,stephenmichaelf/corefx,stormleoxia/corefx,yizhang82/corefx,billwert/corefx,fernando-rodriguez/corefx,alphonsekurian/corefx,khdang/corefx,krk/corefx,shiftkey-tester/corefx,mokchhya/corefx,ptoonen/corefx,jhendrixMSFT/corefx,rjxby/corefx,destinyclown/corefx,spoiledsport/corefx,khdang/corefx,benpye/corefx,Alcaro/corefx,mafiya69/corefx,pallavit/corefx,nbarbettini/corefx,Chrisboh/corefx,twsouthwick/corefx,fffej/corefx,benjamin-bader/corefx,Ermiar/corefx,stephenmichaelf/corefx,manu-silicon/corefx,dtrebbien/corefx,matthubin/corefx,DnlHarvey/corefx,shimingsg/corefx,kkurni/corefx,josguil/corefx,misterzik/corefx,elijah6/corefx,krytarowski/corefx,mellinoe/corefx,zhenlan/corefx,YoupHulsebos/corefx,FiveTimesTheFun/corefx,erpframework/corefx,ptoonen/corefx,jhendrixMSFT/corefx,VPashkov/corefx,ViktorHofer/corefx,benjamin-bader/corefx,fffej/corefx,billwert/corefx,zmaruo/corefx,Alcaro/corefx,JosephTremoulet/corefx,parjong/corefx,vs-team/corefx,Winsto/corefx,lydonchandra/corefx,krytarowski/corefx,ericstj/corefx,shmao/corefx,josguil/corefx,vidhya-bv/corefx-sorting,CloudLens/corefx,rahku/corefx,dhoehna/corefx,parjong/corefx,BrennanConroy/corefx,ravimeda/corefx,jcme/corefx,CherryCxldn/corefx,spoiledsport/corefx,YoupHulsebos/corefx,CloudLens/corefx,josguil/corefx,tijoytom/corefx,benpye/corefx,dotnet-bot/corefx,krk/corefx,matthubin/corefx,jlin177/corefx,claudelee/corefx,bpschoch/corefx,gabrielPeart/corefx,ericstj/corefx,s0ne0me/corefx,kyulee1/corefx,Alcaro/corefx,krytarowski/corefx,ravimeda/corefx,kkurni/corefx,shahid-pk/corefx,the-dwyer/corefx,jmhardison/corefx,cnbin/corefx,popolan1986/corefx,YoupHulsebos/corefx,thiagodin/corefx,stone-li/corefx,kkurni/corefx,destinyclown/corefx,manu-silicon/corefx,parjong/corefx,shiftkey-tester/corefx,shmao/corefx,ericstj/corefx,billwert/corefx,bitcrazed/corefx,rajansingh10/corefx,dhoehna/corefx,elijah6/corefx,mmitche/corefx,xuweixuwei/corefx,the-dwyer/corefx,s0ne0me/corefx,brett25/corefx,cartermp/corefx,richlander/corefx,shahid-pk/corefx,vijaykota/corefx,weltkante/corefx,misterzik/corefx,huanjie/corefx,n1ghtmare/corefx,benjamin-bader/corefx,alphonsekurian/corefx,mmitche/corefx,JosephTremoulet/corefx,heXelium/corefx,krytarowski/corefx,mokchhya/corefx,iamjasonp/corefx,tijoytom/corefx,erpframework/corefx,gkhanna79/corefx,krk/corefx,wtgodbe/corefx,690486439/corefx,brett25/corefx,alphonsekurian/corefx,shimingsg/corefx,mmitche/corefx,stone-li/corefx,ellismg/corefx,khdang/corefx,comdiv/corefx,khdang/corefx,axelheer/corefx,n1ghtmare/corefx,mazong1123/corefx,ravimeda/corefx,vs-team/corefx,janhenke/corefx,akivafr123/corefx,scott156/corefx,chenxizhang/corefx,axelheer/corefx,Petermarcu/corefx,dhoehna/corefx,ptoonen/corefx,rahku/corefx,gkhanna79/corefx,thiagodin/corefx,claudelee/corefx,pgavlin/corefx,VPashkov/corefx,rjxby/corefx,shana/corefx,lggomez/corefx,xuweixuwei/corefx,nchikanov/corefx,marksmeltzer/corefx,rajansingh10/corefx,CherryCxldn/corefx,cnbin/corefx,huanjie/corefx,jhendrixMSFT/corefx,parjong/corefx,adamralph/corefx,zhangwenquan/corefx,PatrickMcDonald/corefx,twsouthwick/corefx,Frank125/corefx,richlander/corefx,matthubin/corefx,mellinoe/corefx,yizhang82/corefx,xuweixuwei/corefx,stephenmichaelf/corefx,zhangwenquan/corefx,jlin177/corefx,benjamin-bader/corefx,ViktorHofer/corefx,bitcrazed/corefx,rjxby/corefx,cydhaselton/corefx,weltkante/corefx,nbarbettini/corefx,gkhanna79/corefx,andyhebear/corefx,wtgodbe/corefx,vrassouli/corefx,shrutigarg/corefx,BrennanConroy/corefx,ravimeda/corefx,gkhanna79/corefx,tstringer/corefx,Yanjing123/corefx,gregg-miskelly/corefx,dotnet-bot/corefx,bpschoch/corefx,rubo/corefx,ravimeda/corefx,shrutigarg/corefx,ericstj/corefx,larsbj1988/corefx,adamralph/corefx,jmhardison/corefx,brett25/corefx,manu-silicon/corefx,s0ne0me/corefx,Chrisboh/corefx,zmaruo/corefx,chaitrakeshav/corefx,andyhebear/corefx,shana/corefx,PatrickMcDonald/corefx,ViktorHofer/corefx,mmitche/corefx,Petermarcu/corefx,SGuyGe/corefx,viniciustaveira/corefx,scott156/corefx,Jiayili1/corefx,wtgodbe/corefx,stone-li/corefx,dsplaisted/corefx,weltkante/corefx,axelheer/corefx,jhendrixMSFT/corefx,marksmeltzer/corefx,stormleoxia/corefx,twsouthwick/corefx,pallavit/corefx,dtrebbien/corefx,gregg-miskelly/corefx,erpframework/corefx,pallavit/corefx,akivafr123/corefx,misterzik/corefx,lggomez/corefx,the-dwyer/corefx,YoupHulsebos/corefx,seanshpark/corefx,PatrickMcDonald/corefx,shmao/corefx,heXelium/corefx,shmao/corefx,Jiayili1/corefx,jcme/corefx,mafiya69/corefx,EverlessDrop41/corefx,Jiayili1/corefx,jlin177/corefx,ellismg/corefx,vs-team/corefx,dotnet-bot/corefx,mazong1123/corefx,MaggieTsang/corefx,Winsto/corefx,tijoytom/corefx,cartermp/corefx,JosephTremoulet/corefx,anjumrizwi/corefx,YoupHulsebos/corefx,jeremymeng/corefx,chenxizhang/corefx,mokchhya/corefx,mazong1123/corefx,krytarowski/corefx,nbarbettini/corefx,mellinoe/corefx,rajansingh10/corefx,MaggieTsang/corefx,EverlessDrop41/corefx,the-dwyer/corefx,elijah6/corefx,lydonchandra/corefx,jcme/corefx,mafiya69/corefx,janhenke/corefx,Jiayili1/corefx,twsouthwick/corefx,viniciustaveira/corefx,twsouthwick/corefx,dkorolev/corefx,anjumrizwi/corefx,CherryCxldn/corefx,josguil/corefx,comdiv/corefx,dotnet-bot/corefx,weltkante/corefx,axelheer/corefx,yizhang82/corefx,weltkante/corefx,dsplaisted/corefx,gkhanna79/corefx,alexperovich/corefx,billwert/corefx,elijah6/corefx,fgreinacher/corefx,erpframework/corefx,the-dwyer/corefx,thiagodin/corefx,kyulee1/corefx,ravimeda/corefx,nelsonsar/corefx,cydhaselton/corefx,rahku/corefx,akivafr123/corefx,ptoonen/corefx,richlander/corefx,mellinoe/corefx,shahid-pk/corefx,manu-silicon/corefx,zmaruo/corefx,pgavlin/corefx,mazong1123/corefx,yizhang82/corefx,mafiya69/corefx,oceanho/corefx,oceanho/corefx,nbarbettini/corefx,mazong1123/corefx,cydhaselton/corefx,Frank125/corefx,arronei/corefx,jeremymeng/corefx,Chrisboh/corefx,fffej/corefx,billwert/corefx,cydhaselton/corefx,VPashkov/corefx,akivafr123/corefx,ellismg/corefx,dkorolev/corefx,iamjasonp/corefx,cydhaselton/corefx,seanshpark/corefx,the-dwyer/corefx,nchikanov/corefx,benjamin-bader/corefx,nchikanov/corefx,JosephTremoulet/corefx,jcme/corefx,tstringer/corefx,YoupHulsebos/corefx,cnbin/corefx,dhoehna/corefx,lydonchandra/corefx,janhenke/corefx,SGuyGe/corefx,alphonsekurian/corefx,chenkennt/corefx,jcme/corefx,stone-li/corefx,rahku/corefx,benpye/corefx,rubo/corefx,Frank125/corefx,matthubin/corefx,benpye/corefx,iamjasonp/corefx,tijoytom/corefx,larsbj1988/corefx,dotnet-bot/corefx,ptoonen/corefx,seanshpark/corefx,chenxizhang/corefx,nchikanov/corefx,benpye/corefx,Petermarcu/corefx,fernando-rodriguez/corefx,rubo/corefx,kkurni/corefx,thiagodin/corefx,adamralph/corefx,jcme/corefx,krk/corefx,mokchhya/corefx,JosephTremoulet/corefx,viniciustaveira/corefx,Priya91/corefx-1,shmao/corefx,heXelium/corefx,benjamin-bader/corefx,alphonsekurian/corefx,kyulee1/corefx,tstringer/corefx,dhoehna/corefx,cnbin/corefx,nchikanov/corefx,shimingsg/corefx,vrassouli/corefx,claudelee/corefx,popolan1986/corefx,alexperovich/corefx,SGuyGe/corefx,ericstj/corefx,ptoonen/corefx,690486439/corefx,690486439/corefx,uhaciogullari/corefx,gabrielPeart/corefx,zhenlan/corefx,ptoonen/corefx,josguil/corefx,chenkennt/corefx,andyhebear/corefx,bpschoch/corefx,jeremymeng/corefx,DnlHarvey/corefx,kyulee1/corefx,shana/corefx,lggomez/corefx,shrutigarg/corefx,tstringer/corefx,parjong/corefx,shiftkey-tester/corefx,Priya91/corefx-1,Petermarcu/corefx,richlander/corefx,billwert/corefx,kkurni/corefx,alexperovich/corefx,Petermarcu/corefx,destinyclown/corefx,jhendrixMSFT/corefx,yizhang82/corefx,n1ghtmare/corefx,stormleoxia/corefx,kkurni/corefx,mazong1123/corefx,weltkante/corefx,seanshpark/corefx,jhendrixMSFT/corefx,comdiv/corefx,Chrisboh/corefx,stephenmichaelf/corefx,shahid-pk/corefx,marksmeltzer/corefx,comdiv/corefx,dkorolev/corefx,lggomez/corefx,SGuyGe/corefx,zhenlan/corefx,elijah6/corefx,uhaciogullari/corefx,zhenlan/corefx,JosephTremoulet/corefx,rahku/corefx,rjxby/corefx,weltkante/corefx,janhenke/corefx,Ermiar/corefx,alexperovich/corefx,axelheer/corefx,Priya91/corefx-1,the-dwyer/corefx,marksmeltzer/corefx,claudelee/corefx,jlin177/corefx,zhangwenquan/corefx,alphonsekurian/corefx,Alcaro/corefx,690486439/corefx,stormleoxia/corefx,lggomez/corefx,fgreinacher/corefx,rahku/corefx,dkorolev/corefx,Priya91/corefx-1,mokchhya/corefx,shimingsg/corefx,chaitrakeshav/corefx,zhenlan/corefx,stephenmichaelf/corefx,MaggieTsang/corefx,krytarowski/corefx,690486439/corefx,alexandrnikitin/corefx,bpschoch/corefx,MaggieTsang/corefx,MaggieTsang/corefx,twsouthwick/corefx,mafiya69/corefx,chenkennt/corefx,pgavlin/corefx,gkhanna79/corefx,vijaykota/corefx,mazong1123/corefx,Frank125/corefx,cydhaselton/corefx,DnlHarvey/corefx,iamjasonp/corefx,wtgodbe/corefx,JosephTremoulet/corefx,nelsonsar/corefx,chaitrakeshav/corefx,mafiya69/corefx,huanjie/corefx,larsbj1988/corefx,PatrickMcDonald/corefx,gabrielPeart/corefx,benpye/corefx,alexperovich/corefx,nbarbettini/corefx,DnlHarvey/corefx,fgreinacher/corefx,KrisLee/corefx,lggomez/corefx,akivafr123/corefx,mmitche/corefx,parjong/corefx,cartermp/corefx,ellismg/corefx,jeremymeng/corefx,anjumrizwi/corefx,spoiledsport/corefx,cartermp/corefx,krk/corefx,shmao/corefx,rjxby/corefx,huanjie/corefx,dsplaisted/corefx,arronei/corefx,jmhardison/corefx,CloudLens/corefx,rubo/corefx,fernando-rodriguez/corefx,mmitche/corefx,Ermiar/corefx,Ermiar/corefx,dtrebbien/corefx,popolan1986/corefx,manu-silicon/corefx,Petermarcu/corefx,Ermiar/corefx,gabrielPeart/corefx,zmaruo/corefx,vijaykota/corefx,tstringer/corefx,DnlHarvey/corefx,Chrisboh/corefx,tijoytom/corefx,ViktorHofer/corefx,dhoehna/corefx,shrutigarg/corefx,KrisLee/corefx,krytarowski/corefx,ViktorHofer/corefx,dtrebbien/corefx,cydhaselton/corefx,dotnet-bot/corefx,tstringer/corefx,khdang/corefx,anjumrizwi/corefx,alexperovich/corefx,iamjasonp/corefx,shimingsg/corefx,Ermiar/corefx,s0ne0me/corefx,marksmeltzer/corefx,mmitche/corefx,Yanjing123/corefx,manu-silicon/corefx,n1ghtmare/corefx,Jiayili1/corefx,lggomez/corefx,axelheer/corefx,YoupHulsebos/corefx,rjxby/corefx,shmao/corefx,alphonsekurian/corefx,MaggieTsang/corefx,elijah6/corefx,wtgodbe/corefx,parjong/corefx,nelsonsar/corefx,uhaciogullari/corefx,vidhya-bv/corefx-sorting,zhangwenquan/corefx,ellismg/corefx,nchikanov/corefx,stephenmichaelf/corefx,cartermp/corefx,seanshpark/corefx,shimingsg/corefx,tijoytom/corefx,janhenke/corefx,n1ghtmare/corefx,jlin177/corefx,ellismg/corefx,ericstj/corefx,nbarbettini/corefx,oceanho/corefx,vidhya-bv/corefx-sorting,alexandrnikitin/corefx,scott156/corefx,shahid-pk/corefx,lydonchandra/corefx,brett25/corefx,pallavit/corefx,gregg-miskelly/corefx,zhenlan/corefx,krk/corefx,oceanho/corefx,marksmeltzer/corefx,heXelium/corefx,iamjasonp/corefx,manu-silicon/corefx,rubo/corefx,shana/corefx,rahku/corefx,fffej/corefx,seanshpark/corefx,ericstj/corefx,CloudLens/corefx,jlin177/corefx,KrisLee/corefx,DnlHarvey/corefx,scott156/corefx,nelsonsar/corefx,BrennanConroy/corefx,ravimeda/corefx,stone-li/corefx,seanshpark/corefx,josguil/corefx,richlander/corefx,billwert/corefx,stone-li/corefx,PatrickMcDonald/corefx,Ermiar/corefx,richlander/corefx,Priya91/corefx-1,FiveTimesTheFun/corefx,VPashkov/corefx,iamjasonp/corefx,bitcrazed/corefx,jmhardison/corefx,uhaciogullari/corefx,alexperovich/corefx,marksmeltzer/corefx,Yanjing123/corefx,SGuyGe/corefx,dotnet-bot/corefx,chaitrakeshav/corefx,shahid-pk/corefx,larsbj1988/corefx,Yanjing123/corefx,shimingsg/corefx,alexandrnikitin/corefx,yizhang82/corefx,gkhanna79/corefx,zhenlan/corefx,yizhang82/corefx,andyhebear/corefx,vidhya-bv/corefx-sorting,wtgodbe/corefx,pallavit/corefx,ViktorHofer/corefx,alexandrnikitin/corefx